What is the difference between a 1997 Volvo 7.4 gi and a 7.4 gsi? It has mpi injection. Is it just cam and computer programs?

This may help

Volvo Penta 7.4 Gi vs GSi rev limiter - Page 2 - Offshoreonly.com

and from searching for 1997
7.4L Gi 1997-2001 4200-4600
7.4L GSi 1997 4800-5200

I believe they also had different style intakes. The Gi had the stock GM truck intake and the GSI had the Merc style racing intake (like on the 500EFI).