Cross-dressing, Trapping

Not the wrong place, but this board is essentially archived since there's a "tips" board on TranCHAN. Anyway, the difference is that a trans person is transitioning, or plans to. A trap is a person who passes for the opposite sex. It was originally used for people who were just amazing cross dressers (Line Trap, etc), but easily applies to trans people who actually pass.

You could claim that "trap" is rude to trans people, or specifically to people who aren't passable. The reality is that humans care about looks first, and personality later—especially when it comes to nudity/porn. Also, this is the Internet, and people who don't want their feelings hurt can cancel their Internet service and read some social justice pamphlets :p