Monster of the Week is a game that can I only really think of as being without the sex and angst. That undersells what it offers and tries to achieve.
Whereas both games have deep roots in the Buffy series, Monsterhearts takes the sexual angst of the TV show and makes it explicit via teen horror films. MOTW on the other hand focuses on the action and literal monster-fighting throwing in similar shows ranging from Dr. Who to X-Files. The result is less shocking, enticing and transgressive but perhaps much more flexible and varied to play. It might also be more appealing to people who find Monsterhearts too full on.
For the most part the game has little new to offer, there are playsheets that do a good job of representing the various archetypes of Buffy with enough variety to encapsulate a wide range of TV shows.
The GM Moves, Agenda and Principles are sound but for the most part because they have been thoroughly road-tested in Apocalypse World itself as well as its many children.
The real area of distinction is in the scenarios that shape the narrative of the game. MOTW is literally about episodes of monster hunting. If you find and defeat the monster the world is a better place, if the monster find and defeats you then your monster-hunting gang is just going to be names on the victim list.
If you don't know Monsterhearts see these Thee Rapture