Ever since his creation, there has been a natural temptation to compare Spider-Man against Superman. As many have observed, the most interesting aspect of Spidey is his humanity. In his personal life, he was Peter Parker, a powerless kid struggling to help support his Aunt and keep his own social life from collapsing around him - a clear contrast to Clark Kent, confident media personality.
Then also as a super-hero, Spidey was far less Super than Superman. While Supes could fly at faster than lightspeed, reverse time, move planets and travel to distant suns, Peter's powers were far more mundane - and for that, far more interesting.
With the creation of the Iron Spider Costume, Spideys' powers and appearance were naturally compared with those of Iron Man, the suit's inventor. But in fact, when you look at the list of powers - super-vision, super-hearing, flying, bullet-proof, etc., it's hard not to make a comparison with Kal-El.