The change logs I found in old threads were now dead dropbox urls (except for this photo of someone’s edited chips), but you can browse the 3E base set chips here and compare yourself.
The big overhaul between the editions was Combine gaining -$1, which prompted a lot of changes to other chips too. 2E chips play fine under 3E rules for the most part, but a couple of characters are a bit too good and the following changes are usually recommended:
Main: +chip + pig
Reaction: Reflect any gems sent to a player to the bank. (Just trash them.)
Hex of Murkwood
Each opponent gains a wound or discards two wounds.
Additionally, there are actually two versions of 2E around, as there was an upgrade pack for it that included screens, playmats and three new bank chips, but also slightly rebalanced character chips. I don’t remember what exactly was affected there, but if you have just the base 2E then Val’s Burst of Speed at least is something you may or may not want to change.