I know that there are differnet types such as the regular dark brown on tan or albino but I never heard of royals or spiders or any other name like that. What are the differences?

I have had my snake, D, for 4 1/2 yrs I got him the day of his 1st shed and he is now right at 4ft and eats a med. rat every 2 weeks or so. He is a regular black and tan snake. What would he be called?

Also is he the right size for his age? I don't think he is big enough but I want to know for sure.

Thanks