These two have nothing almost nothing in common. Ones a wisecracking protector of humans the others is a murderous insane psychopath. Big whoop, tell jokes in battle and they wisecrack. So does Spidey.
I've played it and they have athstetacally have very few similarities like their weapons and maybe there red and black outfits. But that's where it ends, they're characters as far a roles, personalities and situations from who they are and what they do are completely contrasted to each other.
A lot of people think they'd be buddies but Dante like it or not has moral code like Spider-Man and less patience with other loud mouthed morons like him. Deadpool is a less than stable moron who has no limations or even decency to human salvation.
If anything Spidey has more in common with Dante if he was compared to anyone from Marvel. Notice that Deadpool and Dante represent all of Spidey's traits if he was the jock in highschool or mostly a less responsible superhero basically what he would become if uncle ben didn't get killed by his recklessness.