These days I was somehow trying to pay attention to my feelings and thoughts in that moment and compare that set of things with the things I remember in a memory.
What I noticed was that I have more things that are in my attention when actually leaving the event vs when remembering it.
The present experience has a combination of sounds and smells and visual things and emotions and the way the skin feels when touching the insides of the jeans and the way our tongue feels a bit dry and a memory that comes about something a bit similar, etc.
But when we remember the memory, we only perceive a projection of the actual experience.
Open to discussion. Idea in progress.
Furthermore, the brain is a pattern-matching system. It will extract information that is most memorable (highest entropy) and keep it. Certain situations which are stressful or emotional (eg: a surprising or frightening event) will release norepinephrine which makes memories stronger.
Finally, the brain applies tons of heuristics to "fill in" parts of the memory that are not that different from regular experience. It will also pay more attention to things that confirm your biases: https://www.e-counseling.com/articles/what-is-selective-memo...
If you're interested in learning more, this is a great text summarizing many research studies in modern cognitive science and psychology:
https://www.goodreads.com/book/show/18090066-the-owner-s-man...
https://play.google.com/store/books/details/The_Owner_s_Manu...