If I understand correctly, loli only refers to cartoon depictions of preteen girls (and maybe roleplaying with that theme). Being attracted to actual preteen girls is just pedophilia.

(At least that's what loli fans say. I've always been a bit confused by the distinction — I've known people into loli and shota who seemed to find actual children as unappealing as any normal person does, but I can't quite figure out why a person would be turned on only by a cartoon and not the real thing.)