Each animatronic has different variations you can pick from the variations menu. Here are what some words mean:
Normal - The animatronic’s default variation.
Classic - The animatronic’s FNAF 1 version
Withered - The animatronic’s FNAF 2 version
Nightmare - The animatronic’s FNAF 4 version
Off-Stage: What the animatronic looks like when they are off the show stage in FNAF 1 and 2.

Freddy Fazbear: Normal, Classic, Withered, Nightmare
Bonnie: Normal, Classic, Withered, Nightmare
Chica: Normal, Classic, Withered, Nightmare
Foxy: Normal, Classic, Withered, Nightmare
Fredbear: Normal, Nightmare
Nightmare: Normal, Nightmare
Springtrap: Normal, FNAF3
Toy Freddy: Normal
Toy Bonnie: Normal, Shadow Bonnie
Toy Chica: Normal, Off-Stage
Mangle: Normal, Pre-Mangle
Balloon Boy: Normal
Puppet: Normal