There are many parts to Ethereum and it’s PoS system so I don’t think you will be able to grasp it all in a short read. This is a good start:
https://eth2.incessant.ink/book/00__introduction/00__forewor...
https://eth2.incessant.ink/book/00__introduction/00__forewor...
Bitcoin is a very simple system and very limited in its capabilities, but as far as modern blockchains go it is like the early room-size computers, Ford Model T, or Wright Flyer.