Answering my forty-fourth question!
Give an ask to Aaron, get an Aaron response (when the question isn't hijacked.)
Yes, they're intentionally nearly identical; for obvious reasons. Honestly though, there isn't much difference between the two except ever-so-slight hair differences, the fact that Gwen is usually at least somewhat more expressive than Jen, their rankings, their age.. and of course the fact that Jen is flatter than Gwen, obviously. (Also Jen technically has lighter fur than Gwen [even if it isn't noticeable, if you inspect their fur colors, they ARE different], and the fact that she has "Pancakes" written on her shirt, THAT'S a dead giveaway.)
Anywoof, aside from maybe some parts super far along in the comic or something~ These two won't really be shown next to each other, so you don't need to worry about confusing them. If there's a mopey looking full dark-brown woof next to a buff sandy colored woof and a smaller red woof, you've got Gwen. If it's a mopey dark-brown looking woof next to a white woof and light brown woof, you've got Jen.
(It's weird, you'd think Jen would be the bustier one.. But I guess that's how her genes worked out.)