There is the body and there is the Self, between them is the mind, in which the Self is reflected as “I am”.
Because of the imperfections of the mind, its crudity and restlessness, lack of discernment and insight, it takes itself to be the body and not the Self.
There is a difference between awareness as reflected in consciousness and pure awareness beyond consciousness. Reflected awareness, the sense “I am aware” is the witness, while pure awareness is the essence of reality. Reflection of the sun in a drop of water is the reflection of the sun, no doubt, but not the sun itself. Between awareness reflected in consciousness as the witness and pure awareness there is a gap, which the mind cannot cross.
“Nisargadatta Maharaj”