Both retellings put a more modern spin on the fairytales they represent: restlessness, adultery, death. The princes are interesting characters in particular in both Fables and Into the Woods. Instead of giving us the typically suave, charming men we've read about who instantly fall in love with their fair beauties, these princes have no problem with cheating on their new wives with new women, some expected some not (like the Baker's Wife in Into the Woods). Both retellings seem to point out that the men who have been good-looking all their lives are the ones who will go down the wrong path, whereas the Beast in Fables is still a devoted, loving husband: his only complaint is that lack of money has put a strain on his marriage with Beauty. Both stories have put more power in the hands of the so-called "damsels in distress." Cinderella in both versions is a force to be reckoned with; she goes out and get what she wants.
Both retellings also stay relatively true to their originals, in the major details anyway: Rose Red and Snow White are still sisters, Cinderella's stepsisters' eyes are still plucked out, the young maidens end up with their princes at some point, Blue Beard's reputation precedes him. The Grimms would have never made their young women sexual creatures, nor would they have had their narrator gobbled up by a giant.