The Vampire Diaries published way before The Twilight Series. People only turn into vampire if they kill by a vampire AND the vampire feed his/her blood to the victim. They also have a special rings to allow them to walk under the sun. They can't enter people's home unless they got invited in.
i have not read the books, but TVD is very popular in the US also.
Then how come Bonnie (the witch) did not turn into a vampire? She was bitten by something (forgot which vampire :p) and fed by Stefan's blood, but still was a human.
I know it's popular in US & Cananda, but hard to not compare Stefan to Edward, especially I am a die-hard fan of Cullens (though New Moon Movie was a crap).
Even so, I would keep watching this TV show as I had already started the beginning and must finish till its end.