Re: [witchcraft] newbie, but
In short:
1) Most BASE rigs (there is one exception, but it is not widely used) have only one canopy. This canopy is packed in a manner similar (but not identical) to a skydiving reserve.
2) BASE rigs are far simpler than skydiving rigs (primarily because they have no reserve system).
Traditionally, a BASE rig was a velcro closed, single parachute system. However, modern BASE rigs include both velcro and pin-closed containers. Virtually all are still single parachute systems, designed exclusively for fixed object jumping.
There are lots of other differences (for example, no TSO requirements, different pack tray shape and orientation, etc), but that's the gist of it.