Diario de nat_geeo

So far I've found these two juvenile ratsnakes (and these are the only two I have to go off of) and one of them exhibits a grey background with black markings on the dorsal side, and the other one's pattern is black background with grey markings. I am wondering if this is any indication whether one of them is black/grey combination and one of them is either just a black, or grey ratsnake (and vice versa). Does anyone have particular knowledge of the specifics between black vs. grey ratsnakes that can give me some sort of answer. Or at this point are they all just combinations of the two?