Size is the most obvious difference between snow crab and king crab. As you can probably guess, king crab tend to be much larger in size than snow crab, but (interestingly enough), their legs are actually shorter! Snow crabs, though smaller, have longer legs. Also, the shell on a king crab’s legs is much thicker and spikier than the shell of a snow crab, making it harder to crack.
Both options are great for this “crab bake” application, though, so don’t stress and just grab what you can find!