There's also a few changes in their body shapes (which isn't as obvious in the screenshot from the PSU collab video).
Ethan is a bit thinner, Karen has a smaller bust and her ears go out farther.

In general, I think these two are some of the better looking event NPCs to be added to the game recently, especially when I compare them to Jeane from PSO2es....

Hoping they add Laia in part 2.