1998 Oldsmobile Silhouette Cruise works speedometer does no

What do I need to fix/replace when the speedometer doesn't work but the cruise control works fine.

Do they both use the same speed sensor or does the cruise control use the sensors on the wheels.

I had a 1994 4x4 silverado and the cruise control would not allow the rear wheels to spin on ice. It would just gradually slow down and eventually the cruise control would shut-off. This made me think that it at least monitored the passive wheels when the cruise control was on. How else could it know that the vehicle was beginning to spin?

I am hoping that the silhouette just needs a speed sensor, but if that is what the cruise uses, then it must be working fine.