Oooh Brian where to begin to answer that question...
There is main Marvel continuity. This is where the original Spider-Man, Peter Parker resides, the one who has been active since Amazing Fantasy back in 1961...
But there are a number of comics featuring him, including The Amazing Spider-man, Spider-Man, FF (The replacement Fantastic Four Title) and The Avengers. There is also a junior title aimed at younger kids, set outside regular continuity.
There is a sometime Spider-Girl title set again outside regular continuity, but featuring a future Peter Parker and his daughter.
And then there is the Ultimate title, set in a fresh continuity with no connection to the main Marvel continuity. And this is the Spider-Man who has died.