I think it comes down to what's both available & legal where you are, the cost difference, & the personal preference of YOUR snake(s).
To be honest, I've never heard of anyone asking about "brown rats" or "common house" either- as I believe most feeder rats in the U.S. are domestic Norway rats.
Rudeness is the weak man's imitation of strength. Eric Hoffer(1902 - 1983)