Well in his first comic appearance, he (warning spoilers) takes over the role after Peter is killed. At first he wears Peter's suit, but people feel it's in bad taste since Spider-Man just died, so he changes the look of the suit. So he basically becomes the successor to Spider-Man. New suit, younger, and new powers.
Miles for the most part has the same abilities as Peter though. And that's because a scientist stole Peter's blood in an attempt to recreate the formula that created Spider-Man. And Miles' uncle, stole that formula and unknowingly brought one of the Spiders home with him, and that spider bites Miles.
And for the record, Miles Morales is half Black, half Puerto Rican.