PLEASE Clarify my ignorance. 189ci vs 191ci

[SleepyHead98]

1998 Oldsmobile Cutlass: VIN M
Why do I keep seeing 189 ci at the autoparts store when I buy parts, and even several other sites labeling my 98 3.1 l as a 189. Yet other places call it a 191. Is there a difference between the two? I need a new engine. I can get a good one from a 97-8 Lumina--yet the auto salvage guy calls this a 191 CI. Is this the same engine as mine? Will this bolt right in and work just fine with all the sensors I have? Please help me out--this is time sensitive. Thanks!

[maxwedge]

Any Vin code M will work, 97-98 Lumina will work. The displacement is just a metric mis-calculation.