SPIDERman is the one that got bitten by a, yes, SPIDER, when he was a kid. This gave him special SPIDER powers: super strength and agility, the ability to cling to most surfaces, shoot spider-webs, and react to danger quickly with his “spider-sense”.
SUPERman has got SUPERpowers as well. And okay, he is also wearing a red and blue costume, but you can recognize him by his cape. He is the one that van fly without messing up his hairdo, and he has SUPERstrength. Except when in the vicinity of kryptonite of course.