babe: Usually softcore, this niche features girls that are considered extremely attractive. Beautiful and young female models.
fetish: A strong sexual interest in or obsession over some object, body part, or activity. Examples include foot fetish and latex fetish. Also used broadly to describe any non-traditional sex, especially BDSM.
hardcore: Explicit movies or videos that show genitals, especially an erect penis, and often include penetration. In this meaning, "hardcore" is the exact opposite of SOFTCORE. But for many porn videos, it just means an intense or dangerous sexual activity.