These are the portraits that either show a character with improved drawing style and/or who had details changed on them.

Drake, Garrit, Liam, Lupo, Rico, Kael, Damien, Cesar, Ryan and Ace are "just" improved styles without any actually new designs.

Chronos' and Chris' hair was changed. For Chris that means no mane anymore but hair and a beard.

Still kinda figuring out how to draw snakes, so Orion was slightly changed in detail (and it probably wasn't the last one for him)

Kain generally looks more happy rather than smug and had minor changes in details.

Not exactly new details but generally improving some errors on Tyson. The major correction is the mane that might have been interpret as curly hair in the ref.

First real portrait of Rex that I actually feel comfortable with. Plus changed expression.

Huge improvements on Akira's design (especially the eyes) and less grumpy, more cocky expression that better fits his newer personality.

Made Rufus' fur more light

Blaze is adjusted to look closer to Congalala and less simplified. Also added "actual" eyes and some minor changes.

Ryder also got "real" eyes