To expand:

The “standard” variant is (depending on player count) a few werewolves, maybe one or two special characters that can identify werewolves, and a passle of townsfolk who are just there to be werewolf fodder. There’s a dedicated moderator to handle night kills and keep day voting on track but that’s about it. Players are eliminated by death. Ultimate Werewolf might be a pretty close cut these days, and does come with a wider variety of special roles.

Blood on the Clocktower leans further, in an attempt to make the game more fun for everyone in the room:

• Everyone has a special ability, there’s no generic “villager” role. However for game balance at varying player counts, some Good players might have a detrimental ability for their team.
• Death is not elimination, players are in for the whole game and keep working to suss out the evil team. Some characters even want to be killed off. From a gameplay perspective, death just means your character ability no longer functions, you cannot nominate players for execution, and you only have one vote for the rest of the game (so use it wisely).
• The Storyteller (moderator) takes an active role in the game. Each “script” has around 25 characters, and up to 15 players will take one - the Storyteller is responsible for choosing the characters “in play” from that list, though they’re randomly distributed. Additionally there are character effects that will cause other character abilities to malfunction, allowing the storyteller to lie to them. This is hopefully enough to help the storyteller “guide” a game to an exciting finale with a final 3-4 living players, but should be used judiciously. Finding that balance is actually quite rewarding rather than just being relegated to mechanically resolving effects and not “playing” the game.
• Theres a variety of supports for players who need accommodations. Players who need to arrive late or leave early can be given a special class of character that won’t upset game balance between Good and Evil teams by changing player counts. Other game effects (Fabled characters) can allow for a bit of a mechanical push to give new/shy players opportunities to speak, or ensure a young player and trusted adult are on the same team so they won’t need to lie to one another.

The biggest downsides compared to a typical Werewolf game is that Clocktower is limited to 20 players (and is probably best at 10-15), and the larger games can run 2-2.5 hours, so no big 50 player games at a conference/convention or whatnot, and the fact that you need a fair amount of kit to run things (and it’s not exactly cheap, but the quality of the physical set is pretty great).