There are 8 basic alloys of aluminum based on the alloying element(s) (or none for 1000, which is pure) with the 8000 serving as a sort of catch-all for various combinations that don't warrant a category all their own. The total number of formulations is quite large and the properties, machinability, weldability, various strengths, density, resistance to fatigue (and post processing options, such as hardening) vary considerably.
Materials science is a fascinating field.