In some respects, they are both comparable. They are both Grade 1 scrambles and are long narrow ridges with steep drops either side. They both have brief sections of steep climbing, of about the same technical difficulty. Both of them are places to avoid in high wind.
Crib Goch, however, is a ‘bigger’ version of Striding Edge. Everything is more exaggerated. The approach is steeper; the drops are bigger; the climbs are harder, longer and more frequent; there are fewer (basically none) places to escape the ridge if you find it difficult.
A good plan would be to do Striding Edge (on Helvellyn in the Lake District) first, and if you find it okay then progress on to Crib Goch another time.