My favourite thing about both these superheroes is that they are grounded, 'human' so to speak supported and purported by technology. They do not have god given powers like Spiderman or Superman but rise on the basis of the technology they use, their 'suits' and ofcourse staggering wealth. It makes us believe that we could be them if we had all of the above - in short if we were extremely nice looking, fit, tech savvy billionaires.
But as superheroes and their film interpretations go they could not be more different. Their difference lies not in the suits they put on, though they are a reflection of who they are but in the character difference between Bruce Wayne and Tony Stark. They have their similarities - the money, the toys, saving-the-world-phenomena, the parents that they lost when they were young, the companies they run. It plays out like modern man's ruinous dream. But where Wayne is dark and brooding, Stark is known for his quick wit and one-liners. Where Wayne takes himself too seriously, is modest and careful to keep his identity hidden, Stark is almost irritatingly flippant and for lack of a better word, a show-off. And this reflects in the superheroes we love so much.

Iron Man leads us to LA but doesn't explore it. His villians are international terrorists and his desire to don the Ironman suit stems from that. Batman leads us into an obviously New York City-based underbelly of Gotham, unveiling and playing with the concept of fear, anarchy and chaos as real ideas and alter egos of ones self. He broods us into boredom but rises to epic proportions. Unlike Iron Man where you can write a text message, eat some popcorn and come back to the movie, Nolan's Batman draws you in, he engages you. Iron Man is a feel good movie, that you go out discussing happily with friends while Batman makes you introspective and serious.
As similar as they are, their differences stand in stark contrast. If you make me choose, i'd be torn. They play out like almost two separate genres. Just maybe Iron Man in Nolan's hands can be what Batman is or vice-versa but where's the fun in that. Each feeds separate parts of our intellect and both are highly enjoyable.