Hmm, by now it’s hard to remember what is new, and what was in vanilla. I think new Great Wonders were added for C3C (Temple of Artemis, Mausoleum of Mausollos, Statue of Zeus, and Knight’s Templar come to mind). The only changes to existing wonders I can think of are that Shakespeare’s Theater acts as a hospital in the city that builds it (it can grow above size 12), and I think the Tourist Attraction feature is new (certain wonders start producing income after 1000(?) years).
As far as small wonders, the only thing I can think of is that Wall Street requires 5 stock exchanges (I think it used to require 5 banks, and stock exchanges didn’t exist).
You may want to review these threads.
This one is a guide to all great wonders in C3C – you are probably better able to tell what changed than anyone else.
This one is a list of the changes that were made in C3C – I’m not sure it’s really complete, and I don’t know if there were other changes from vanilla to PTW that you wouldn’t know about, but they should be good places to start.
EDIT - The first post in the C3C changes thread didn't look that complete to me, but if you continue through the thread to Arathorn's posts, I think it probably covers everything.