I figure the one just sat around for longer, as I've had extra blue-y cheese develop in my own fridge. Just never seen such a striking difference at the store, which I found mildly interesting.
Maybe just a specific variety of mould that doesn't cause that.
There are 2 varieties of milk bacteria that make curd and yoghurt.
Then a few varieties of yeast for bread, beer etc.
Makes sense to be one for cheese.