Because Linux is open source and each group has a different idea on the direction it should go. They are all linux at their core, but they all have different use cases.

Bazzite and Zorin are both great options for leaving Windows for the first time. Bazzite is generally more gaming focused but Zorin is a better desktop in my limited experience of both. Bazzite for example is more locked up on OS files, so it's harder to break in some regards. But it also bakes drivers into the image and they only get updated on the next release. Afaik you can't tinker with the drivers much but I'm not experienced enough to say 100%.