Same classroom and sim training as PIC. Only the checkride is different. Last type I did there, my sim partner's (SIC only) ride was about half the time and items of the PIC ride. If memory serves, 2 approaches, (1 precision, 1 non-precision) and 1 V-1 cut. I cannot remember if he did a single engine approach or not. I don't think so. no fires or system failures (other than V-1)like the PIC ride.
The PIC type ride covers one of everything.
So to answer the question, SIC training is the same as PIC training, you just do not have to demonstrate all of it on a checkride like the PIC does. PIC ride is to ATP standards, I think the SIC ride only requires commercial standards.
As always your milage may vary, Some companies require the SIC to be the same as the PIC. F/S will modify the ride to meet the customer company requirements.
The ride I described was for part 135 SIC and that was pretty bare bones, so I doubt that the part 91 SIC ride is any different.