Bazzite is the gaming spin, and basically the starting point for people that want a couch console / HTPC / stationary Steam Deck imo.
Bluefin and Aurora are put together with general computer use in mind, and then both of them can be swapped to a developer-focused “-dx” image with a single command, that adds VS Code and a bunch of development tools.
It just changes the starting point based on if your PC is mainly for work, or mainly for play. All three are just as capable to be set up for whatever.
PCPartPicker can filter for card length (in millimeters as opposed to inches, but still) and that should help with narrowing down your choices. Most GPUs have some variant that’s shorter in length, but they might just charge a bit of a premium for it.