what's the difference between mutants and metahumans?

Why are people afraid of mutant heroes but worship metahuman heroes? What's the difference? One is born with the abilities and one gets them later on in life through accidents. Why do people not view spiderman, daredevil, fantastic four as mutants!?

You just answered your own question. One is BORN human and the other isn't. Apparently that makes all the difference in the Marvel World.

like Xavier says. mankind fears what it doesn't understand, whilst these metahumans aren't completely understood, they can be explained because of an accidnt. Being born that way implies a purpose behind the powers and people don't understand this. hence the poor old mutants are treated with fear or hatred usually.........

That answer is wrong take the grandson of the flash he was born with his abilities so doesn't that make him a mutant not a metahuman

DC doesnt have the rampant mutant phobia DC does, though, so you shouldnt factor that Company into your equation.

people in comic books always had a problem with mutants because it is an allegory on racism and social/genetic inferiority.

In Marvel comic books, yeah.
If anything, DC has done it most prominently with aliens.