When a man surrenders himself as a slave to the divine Lord he realizes at the end that all his actions are the actions of God. He loses his mine-ness.
This is what is meant by ‘doing the will of God’. This is Siddhanta [the final view; the settled conclusion]. When a man realizes that he has lost his ahamkara (I-ness) and that he is not different from Isvara, he is a jnani. This is Vedanta.
But see! The goal is the same. There are two ways open to one: bhakti and jnana. A bhakta surrenders to God and rests secure in His protection. A jnani knows that there is nothing beside the Self and so remains happy.
One must adhere firmly to either of these courses. This path is the highest of all and suited only for advanced aspirants. Those who follow the other paths are not ripe for this until they become advanced on their own paths. [See Spiritual Instruction 2.2]
Thus it is really by the Grace, whether Guru, Self, etc. that they are brought to this highest path. Of course, they might have practiced the other paths in former existences and thus were born ripe for this one; others try the other ways and after progressing finally turn to Self-enquiry. But the last laps of all paths are the same — surrender of the ego.