This whole path from Guide to Guru and from being a Disciple to Devotee to Divine may not happen with a person in One lifetime. It may happen in several lifetimes.
Oftentimes people use these words "Disciple, Devotee and Devotion" without understanding their true meaning. Without knowing the true meaning of these words, that which one is trying to achieve cannot be achieved, because in other words, one doesn't know what it means, to be a Disciple, or Devotee and what is Devotion. It's very easy for anyone to say "He is my Guru, She is my Guru, or I consider you my Guru, or I want you to be my Guru, or You are my Guru or that I am the Devotee of him/her". But until one is truly a Disciple, Guru can't be Guru, until one is in Devotion and becomes a Devotee, Guru/Self/Divine can't play their Role and transmit Wisdom, Shakti/Power in any way. So it's very important to understand what it means to be a Disciple, Devotee and what exactly is Devotion. Disciple or Devotee is a "receiver of wisdom, energy, life and everything", and it matters to understand what do we mean by "receiver" and then one can try to be a "good receiver", else it won't matter, it won't work, one will simply waste time. All of you have the body, mind, and emotions and you also have lots of methods, philosophies, opinions, prejudices, experiences that you gathered, developed while living life. When you start walking Spiritual Path consciously or may it be a Corporate/Business Path, then you use all that you have. You utilize the body, mind, emotions, and everything else that I mentioned above in order to reach the goal. Spiritual Journey has Liberation as a Goal, Corporate/Business goal could vary from person to person, but there is a Goal that one has in mind, before embarking on any long, arduous journey. Now suppose while on your journey you realize that you are not going in the right direction, you are not making progress, you are not getting what you were supposed to get, you are not reaching anywhere, then you will start looking around, looking towards those who have successfully achieved the goal that you are trying to achieve. You will realize that you don't understand those things which are necessary for success, you will accept that you need guidance from someone. In other words, you will start looking for a guide, or a mentor. As soon as you find such a Person/Guide/Mentor, you will reach out to him/her to clarify your doubts, you will try to gather knowledge from him/her, you will start sharing your concepts, philosophies, prejudices, experiences and even your decisions, so you can have his/her point of view. You will use Guide's/Mentor's perspective and YOUR MIND to pursue your journey. Regardless of Guide's specific instructions, you will end up doing, which you anyways had in your mind, you looked for Guide for validation, verification of your own mind, which you may get sometimes, and may not at other times. Now suppose after pursuing your journey with the help of Guide/Mentor, you still did not reach your goal, instead, you hit the major setback and you achieved nothing, lost time, energy, resources and your mind went NUMB. You felt clueless, as to how to proceed further, you hit a dead end and you find yourself completely in the dark. You struggled with this setback for some time and you finally ACCEPTED that it's not going to work through your mind. This acceptance helped you push your mind aside, and you started looking for a Guru.
When you found a Guru, you started listening and following his instructions PRECISELY. Your own mind stopped causing much resistance and whenever a doubt arose, you reached out to Guru and got the clarification. Even if you did not understand that at once, you had trust, faith that someday you will understand it completely. You placed your trust, your faith in the Guru, realizing that Guru won't misguide you and Guru himself/herself has reached that goal, which you are trying to achieve. This is who and what a DISCIPLE is. Disciple surrenders his mind, becomes no-mind and pushes his own experiences, philosophies, methods, prejudices, opinions aside, and keeps doing what Guru is asking to do. Even at times when you do not want to do, you keep doing it, because in the past you got burnt when you tried to use your mind. This is the stage where you are practicing the "Full Surrender of Mind", where you are implementing that, where you start living life with Surrendered mind. Time to time there will be resistance in you, but over the period of time, it will vanish and you will become truly a very good Disciple.
After few years of being a Disciple, slowly you start realizing that life is moving in the right direction, you crossed some major milestones without much problem and it's working, success is not too far. Realization of that started "opening your heart". Love started cultivating in you towards your Guru. Your faith, your trust now converted into Love. Now your own mind is totally out of the question, it doesn't create any resistance what so ever. You follow Guru's instructions out of love now. This is who and what a DEVOTEE is. A Devotee is the one with No-Mind and Open-Heart. A Disciple is Devotee in Making! Now that you are a Devotee and your Heart is Open, Guru doesn't need to instruct you using words, language. Guru can instruct you through Power/Shakti/Energy. Guru can transform you just by looking because you have become a ULTIMATE RECEIVER. Guru rarely talks to true Devotees, they just live around the Guru in complete Surrender, they understand each other without verbal communication, and they both LOVE each other. A devotee is ALWAYS thinking about Guru only, Guru becomes the "center" of Devotees life. The Devotee finds it painful when Guru is not around, or when he/she is not around the Guru. Love toward Guru starts becoming unconditional. Devotees ONE POINTED MIND is pointed towards the Guru and his HEART has nothing but Guru, devotion for Guru.
Now it gets very interesting. Because the end goal is Liberation, Liberation even from the Devotion towards the Guru, so Guru starts alienating himself/herself from the Disciple, this makes disciple go crazy. The more Guru sends him away from himself, the more heartburns disciple gets. Guru is not trying to torture or punish the Devotee here when Guru knows Devotee is madly in love with him/her, he is simply trying to TURN his Devotion towards SELF/DIVINE/GOD/Devotee himself. The more Guru keeps him away without even explaining the reasons, the more THAT FIRE of DEVOTION burns the Devotee. Devotee starts feeling longing so painful that slowly it becomes suffocating. Day and night devotee burns in this longing, suffers, cries his heart out, and is totally baffled as to what did he do wrong, so Guru is keeping him away, what mistake he made, he simply loved, he just want to love Guru and nothing else he wants in life, he doesn't even want liberation at this point, he wants his Guru's love only, he wants his Guru only and the fire starts going on and on and on inside the devotee. Now Devotion is the FIRE, and Devotee is ON FIRE! Slowly after much suffering through that longing and after much pain, there comes a time, when Devotee is ready to die. Devotee believes that he/she can't take it anymore, Guru doesn't love him anymore, Guru doesn't want him, Guru has abandoned him, then what's the use of this life, why am I still living? Such thoughts start taking the grip on the entire existence of this Devotee. Now Devotee turns towards GOD/Divine. Devotees' complete attention turns towards Divine, he/she starts looking towards Divine in order to get answers like, why did you even create me, why did you send me on this early plane, just to suffer? You also don't love me at all, my Guru doesn't love me either. Why did you do this to me? Do I exist? All such questions now Devotee starts asking from God/Divine. The pain, suffering, longing, fire in Devotee is so much that he actually FORGETS about GURU altogether, now the Focus, Attention, Question is about LOVE. The devotee wants to know if he/she is loved by God at all or not, if even God doesn't love him then one better die, what's the point in living such a life, where no one loves you. This suffocates the Devotee to an extent that he/she stops BREATHING externally, that Fire/Pranic Energy starts flowing from the Central Column, Sushumna Nadi and hits the Crown Chakra, Shakti unites Shiva. And that's it. That's when Devotee gets Enlightened/Awakened. Now, this whole path from Guide to Guru and from being a Disciple to Devotee to Divine may not happen with a person in One lifetime. It may happen in several lifetimes. Also, ANYONE can play Guru for you, when you are ready, when you have renounced the world/mind. Self can play Guru through anyone who can kindle the fire of love, then unconditional love, then devotion. It happens that one ends up loving another person initially and slowly that love becomes unconditional and then that person goes away in one way or the other from one's life and longing starts and love becomes unconditional, the fire of devotion starts burning day and night, and ultimately one Awakens! Not ALL those who love the other unconditionally may arrive at this end, because one may still have not Surrendered completely, and may still have mind/world left to deal with, play with. Now based on the fact if you have surrendered your mind, renounced the world from your mind you become Disciple and Guru can play his Role and be the Guru for you. If you have become no-mind and your heart has opened in love, then you become the Devotee of your Guru and Guru can give you ALL that he/she has and can take you to the Ultimate! Based on your own level you can call yourself Disciple or Devotee or none of these. The same person can play Guide, Mentor or Guru or none of these, depending upon where you are in your journey of life. If you are NOT ready, you will never know that there is a Guru/Self/Divine around you, you will never be able to benefit yourself from the Guru/Self that you may have around unless you are READY! So to what extent you can receive from the Guru depends on upon YOUR CAPABILITY TO SURRENDER your body, mind, emotions, not the Power of Guru/Self. Because Self can play Guru through any person or even Stone if you are ready. Meera was the devotee of Lord Krishna and used to see him in the Stone Statue of him. Such is the power of Devotion and SELF/GURU. You can learn to "live life properly" through a Guide or Mentor, but you cannot start and finish Spiritual Journey until you become a Disciple and then Devotee. It doesn't matter whether you are a Disciple or Devotee of any person or stone or everyone you meet, or the life itself. It's the state of No-Mind, Open-Heart and Fire of Longing is what works through different people, deities, Self/Guru/Divine and helps you reach the Ultimate! Jay Shivay!