Dimensions

There are a few different dimension's or timelines in this universe.

Main Timeline
The main timeline is where super saiyan god and blue come into play. it's the original. Goku beats Frieza on Namek, Gohan kills Cell via help from goku in otherworld, and Goku beats Majin Buu on the planet of the Kai's. Goku meets Beerus ect.

GT Timeline
In this timeline Beerus didn't exist and neither did the other universes. everything happens the same up until where super starts due to the change. Goku becomes super saiyan 4. the shadow dragons show up and super 17 wreaks havok.

Gohan's Spotlight
This timeline is one where Gohan defeats Cell and beats Majin Buu, due to Goku never getting revived after being blown up by Cell, Gohan obtains super saiyan 4, and the Vegehan fusion is born.

Xeno
This timeline begins to stray from the main timeline when the Buu saga begins when Towwa ends up killing Goku, when he's revived he obtains super saiyan 4, and somewhere along the line he gets super saiyan god, giving him god ki and increases his super saiyan 4 strength.