What do you call the crankset system type on the Sram Apex?
Sram apex is a double chainring crankset which uses a GXP (aka Giga-X-Pipe) bottom bracket which is an external bearing bottom bracket.

I think External Bearing or Outboard bottom bracket are both commonly accepted terms, however there are several different incompatible types of external bottom brackets such as hollowtech, GXP, and Ultra Tourque.