Calvus come either in white or black and Comp are orange/yellow. There are many more newly discovered sub species but I highly doubt the a LFS carries any of them.
The calvus will eat any fry/eggs, so they're not a good choice for the breeding tank. I had a comprecissepts (Orange adult) and he looked pretty mean and colorful, but was a bore! He didn't swim around much and always tried eating the smaller fish (Calvus/comp have big mouths ). I wouldn't recommend putting a calvus in a tank that you think may have community fish in it. Other cichlids seem to respect or at least not feel threatened as much by the calvus. Had a semi-aggressive ahli/fryeri and milomo in the same tank, and they all got along very well. Calvus pretty much ignore other fish until it's either hungry or they're trying to get in their cave (which is a required 'must have' for calvus). It makes for easy pairing, but part of the reason they ignore other fish is that they're partially brain dead!