Note: this post’s mainly focused on The Resistance: Avalon (TR:A), but most of this applies to the original The Resistance, as well. The Resistance provides more game play cards and has a sci-fi flavor. TR:A has a medieval/fantasy flavor and its strength relies in its character differences. Same basic gist, though. I don’t own the original game, but I’ve played it.
The Resistance is a hidden role game that’s great for fans of Werewolf (see this entry) and for people who dislike the “dead player” aspect of that game. In Avalon, players play as loyal servants of King Arthur (blue team) who have been infiltrated by the evil Minions of Mordred (red team). Teams are secretly dealt out. Everyone pretends to be on the blue team.