For the most part, a trash service takes away the trash you produce on a daily basis. This can be your cooking scraps, paper, wrappers, etc. None of these items were ever meant to be worth much. These items tend to be small and people produce enough of it to demand a weekly trash service.

A junk removal service specializes in hauling away more bulky items, that at one time may have been worth something, but now are just considered junk.