Arse Technica just had an article on this. (It is very basic and not written for a bike audience.)
https://arstechnica.com/gadgets/2018...-wheeled-tech/
For road bikes, the biggest changes I personally noticed between my latest (2014) purchase and my previous one (1987):
1. Frame materials (although I stuck with steel).
2. Disc brakes.
3. Drive train (especially the transition from freewheel to feehub and much wider gear range).
4. Shifters (I went from downtube friction to Di2).
I got the distinct impression that several of the advances (disk brakes, stems, etc.) originated with mountain bikes.