With enough differences, they can claim it's NOT Star Trek, and therefore not get into trouble with copyright laws and such.
Uhh, no, because the text explicitly references "Captain Jean-Luc Picard of the USS Enterprise
." And despite variations of artistic style, there's no question that the images are meant to represent the characters and sets from ST:TNG. It's just an impressionistic way of rendering them, as we've seen in other Trek comics in the past, like that official movie-prequel mini-comic from Wired
magazine a few years ago.
As long as the comic is being published for free, without any attempt to profit, it's the sort of thing that Paramount/CBS generally allows to exist, like Phase II
and other fan films.