It's even more confusing than that :)
GB200 = 1 CPU + 2 B200 GPUs (packaged together)
NV72 = A rack of 72 B200 GPUs (or 32 GB200 superchips)
Think of GB200 as something like Apple's 'Ultra' chip. Not exactly, but similar. They fuse the chips together with a very fast interconnect (connection).