Superman is in a different universe of power — Deadpool's healing factor just means he dies more creatively.
Deadpool's healing factor makes him virtually immortal, but that doesn't mean he can win fights against beings infinitely more powerful. Superman could throw Deadpool into the sun, freeze him in ice and bury him in the Earth's core, or simply fly him into deep space.
Deadpool's weapons — guns, katanas, explosives — are literally useless against Superman. Bullets bounce off Kryptonian skin. Katanas shatter. Explosives are a mild inconvenience.
The healing factor keeps Deadpool alive through all of this, but alive and winning are very different states. Superman could contain Deadpool permanently without breaking a sweat.
Deadpool can't be permanently killed. His fourth-wall awareness and unpredictability make him... still completely useless against someone who can bench-press the Earth.
Superman can throw Deadpool into the sun. Heat vision, freeze breath, and planet-moving strength make every conventional weapon irrelevant. Superman could simply fly Wade to a dead planet and leave him there.
Superman wins instantly and completely. Deadpool survives because he can't die, but he has literally zero path to victory. This is less a fight and more a comedy sketch.
Deadpool also fights
Superman also fights