I took different things from both, though.
Ginger Snaps was a grimy story about misfits, one of whom suddenly gets hideous power.
Jennifer's Body is the story of a popular girl who loses her remorse and inhibitions. You thought Jennifer had little remorse or inhibition before? Check her out as a fucking demon.
Ginger is a Werewolf. Jennifer is a Ghoul.
Ginger Snaps is a better movie.
Jennifer's Body has the best scene* (actually, the best two scenes**).
*Needy encounters Jennifer covered in a boy's blood, freaks out and drives home. Somehow, Jennifer beat her there, and she's all clean and gorgeous looking. WTF?
Needy is feeling betrayed and confused; Jennifer is feeling high on life and on her own power. Naturally, the two of them start making out. And it takes Needy a good 10 seconds to remember, "Wait, you're a fucking cannibal demon!" Burgeoning teen sexuality > murderous rampage.
**Needy pins Jennifer to the bed. She's got an X-acto knife in hand: it must be done. Needy drives the boxcutter down into Jennifer's chest.
"No," says Needy, "your heart."
Jennifer crumples into her covers. And then her mom walks in and flips on the light. Cut to Needy in an insane asylum.