Exodus 23:20 Behold, I send an Angel before thee, to keep thee in the way, and to bring thee into the place which I have prepared.
John 14:16 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
Angels are messengers, external to our body and souls. They watch over our activities from without. The comforter on the other hand is God in the third person of the Holy Trinity, the Holy Spirit or Holy Ghost. He is not external, He is internal. We have evolved spiritually.
Many religions, even some professing Christ, deny the Trinity, deny God would ever possess man. Possess is the wrong word but is often used to distort our relationship with the Holy Spirit. Possession infers absence of control of the soul. The Comforter does not take control in that sense. We are not puppets on a string. We still have free will. We still have a choice. While the Holy Spirit speaks truth to us, we still have the ability to believe or not.
To what end or purpose is the Spirit given if we are still in control of our actions? Intimacy in relationship is the purpose. We are not in control of the Spirit for He is the power of God in the world. We can see and hear His power enacted in this world as it relates to our obedience of faith. We know that which is done of us, we know what is done of God through this intimacy of relationship. We get to know Him much more intimately, His ways and His will.
What did you think our intimate relationship with God was the end game?