The concept of Batman Confidential admittedly doesn't sound any different than Legends of the Dark Knight, but I'm very excited about Superman Confidential because the first story arc will be written by Darwyn Cooke and drawn by Tim Sale.
I think we've seen enough of Sale's version of Batman (I count 32 full-length issues plus 6 of Catwoman, not to mention covers for Detective and Batgirl) but only four issues of his interpretation of Superman — arguably his best work — so I'm glad DC decided not to give Sale his "default" assignment.
Yet the new piece won't be a simple rehash of his Superman for All Seasons material. According to an interview at Newsarama, Sale says:
The art style I'm using is different, but the innocence that my Superman has is the same. There is more variety in his expressions perhaps, in this version than the one I drew in For All Seasons.
I wanted very much to have a different look than For All Seasons, both because I want that look to be special for the stories I do with Jeph, and because I felt this story deserved its own look. I do think I have matured as an artist since then also, and there will be some difference from that, too.