I haven't played Warhammer Diskwars, but I have played the original. I'm not sure if the new version is drastically different, but the old Diskwars didn't feel very similar at all to me. Diskwars feels more like an open, almost miniatures-like game to me, and combat strategies are very different. Battlelore feels much more "wargame"ish, and requires a very different set of strategies.
I like both, though I haven't played Diskwars in awhile due to the army building setup time and just not having the space or time to organize my stuff lately.