Superman is a superhuman from other planet with extra strength and unknown physical and organs structure. Hulk is an ordinary human evolved by the radiation. The Hulk belongs more to the group of X-Men.
I've never seen Superman have any troubles with any things beside Kryptonite and Louis Lane!
If someone remembered, In the old Superman Movie, he can even turn back time. He can go back when The Hulk is still Bruce Banner and kill him.