What is the difference between black and grey mice?

what is the differences between black and grey mice, other than their color? we have two mice that roam our kitchen one gray and ones black and they seem to act really different. the grey one seems much shyer where as the black one is much more confrontational, and when i yell at it to get back where it came from sometimes it will even squeak a bunch back at me. im wondering if there are traditionally any differences in character or anything?|||I think that more gray Mice are wild and More black Mice are domestic (pets).