A mouse is a mouse is a mouse. Whether it was bred with the intention of being lunch or someone’s pet doesn’t make a difference – it’s not a different species or anything. Generally, but not always, feeder mice are albino and often they are bred to have larger litters to better feed your snake. Generally they aren’t handled very much, therefore they usually aren’t as tame as those destined to be pets. Depending on the source (ie. a bad feeder breeder), they can be poorly bred and have physical or behavioural problems. But, then, some fancy mice breeders are just as bad with this, and some feeder breeders have excellent practices. So, in conclusion, that’s a whole lot of generally’s, usually’s and often’s. Just find a mouse you like and go with it.