Grant it that tVD only has two seasons so far so the plot resemblance are sorta few in counts, plus its both a supernatural show so the odds of plot resemblance are pretty high. But the characters are pretty much, well, they play the same roles and conflicted with same insecurities. As a TV addict, i can't help it but compare and comment.
The VAMPIRE DIARIES - BUFFY the VAMPIRE SLAYER
The Belle-of-the-Ball Heroine: Elena Gilbert - Buffy Summers
In the battle between Elena and Buffy, well if its a physical on-hand combat, it won't be fair to Elana for Buffy has her super strength. Plus, everybody loves Buffy since she is actually the hero of the show and she change the role of the heroine's as the damsel. But I gotta give props to Elena for not being the typical shallow queen bee. Everybody loves her, she's very famous and yet she's not the head cheerleader (thank heavens for that). I love Buffy but I respect the idea of Elena so I think its subjective which you think is better.
The Brooding Eternally tortured Doo-Gooder Vampire: Stefan Salvatore - Angel(Angelus)
The Dark Twisted Vampire: Damon Salvatore - Spike (William the Bloody)
The Mr.Know-All-Supernatural-Stuff-Stocked-in-a-Boring-Job mentor: Alaric Slatzman - Rupert Giles
The Non-Heroic Tasteful Opposite of our Heroine: Katherine Pierce (Katerina Petrova) - Faith
The Witchy Pose Best-Friend: Bonnie Bennet - Willow Rossenberg
The Non-Super-wanna-be-part-of-the-gang dude: Jeremy Gilbert - Xander Harris
The Tactless Insecure yet adorable super: Caroline Forbes - Anya (Anyanka)
The new-to-the-supers-turned-out-to-be-a-werewolf Dude: Tyler Lockwood - Oz
Jenna Sommers - Joyce Summers
(I fear tVD biased fans would tackle me to death)