They are not too far apart tonally, but the Cold Sweat has more lower midrange and bit less output in the upper frequencies. (In the 'air' range, I would say above 7.5kHz)
The Cold Sweat is very 'driving', whereas the Rebel Yell is more 'revealing', and has a bit more in the harmonics department.
If I were to compare the two to blades, the Rebel Yell is a rapier (quick and incisive) and the Cold Sweat is a broad sword (heavier and more crushing).
I would lean towards the Rebel Yell for a single-guitar band rock setting, and the Cold Sweat for metal (especially if you're looking for a heavy NWOBHM tone).