i don't know forza very well, but those two are older, right? because there's a motorsport 7 as well as a "Motorsport" that is between releases of Horizon 5 and 6.
seems like everyone that made racing games went a little nuts around the same time...
Simplifying here, but Motorsports is Forza's sim-style racing game, while Horizons is more of a arcade-like open world experience.
Some people like trying to perfect their technique running the same track over and over, while others just want to drive cool cars really fast. So MS wisely split the game to address those two core markets.
