ACR:
factory smooth tubes / hi-flow filters.
Adjustable suspension (shock compression/rebound and ride height)
BBS Wheels
No A/C (In most ACRs, comfort package adds this option)
No Radio (In most ACRs, comfort package adds this option)
No Foglights.
Different oil filter adapter.
Badging
Factory 5-point harnesses.
I believe the ACR was about a $10K increase on the sticker. I don't know if it's still worth the $10K difference nowadays, but the 01 ACRs are going for in the mid-60's from dealers. That's some portion higher than a regular GTS.