DC-10-10 - initial orders by AA, UA, National... powered by CF6-6 engines
DC-10-20 - ordered only by NW & JL - powered by JT9D-59 engines
DC-10-30 - ordered by European ATLAS & KSSU carriers - CF6-50A (later -50C) - later also operated by AA, UA etc.
DC-10-40 - marketing rebranding before delivery, at NWA's behest, of the DC-10-20 (the nameplate DID NOT CHANGE).
A300B2, B2K, B4 - same engine choices as the DC-10-30
(edit: since I went to the trouble to spell it all out, I found a
more complete version here)