as a huge fan of both, i think we underestimate how much of a democracy U2 is compared to Bruce. he pretty much writes the songs and tells the E Street Band what to play -- yes, it's collaborative, but it's not a democracy at all. just like any Hollywood movie with a heavyweight director is collaborative, but it is not a democracy. it's Bruce's band, period.
i think his music is, and always has been, also less innovative and interesting than U2 (his lyrics, however, are a step above even Bono at his best), and despite the quality of much of The Rising and Magic, it's not too different than what he was producing in 1984. now, this isn't a bad thing at all. it's just a different thing than U2 tries to do, which is start from scratch each and every time.
and at this point in their careers, Bruce knows who he is and how he will be remembered and so there's a kind of "fuck it" quality to what he's doing now -- he's been liberated by the success of The Rising and Magic, he's now a certified national treasure, and no one talks about the 1990s. U2 isn't where he is (not that they've had similar career trajectories), and i do think they can get paralyzed by self-analysis and self-absorption.
and i think at the end of the day what U2 is trying to pull off is harder to do. Springsteen writes music and puts to song powerful stories and ideas about real people and real life. it's a pretty traditional thing, and no one really does it better. U2 uses music to try to get at something different, something more akin to collective transcendence and ecstasy -- it's the difference between telling a story and casting a spell. i think this is reflected in their concerts as well. they're the two best concerts i've ever seen. no one i've seen approaches U2 or Bruce at their best. Bruce is the most energetic, emotional, barnstorming performer i know. U2 has a slippery, almost mysterious 4th dimension when they connect. it's the difference between "Born to Run" and "Streets." arguably, but probably, their best respective live songs. but in the lyrics, in what each song wants to accomplish, you'll find the difference.
one is not better than the other. but i think one is more like capturing lightning in a bottle. and that takes much longer.
and if you don't own the live album from the Seeger Sessions, you really should go get it.