Austin they are Obsoletus nassy snails. They are 1/4 to 1/2 inch. I can get the vibex ones too.
Both are found in the same locations and habitat. Both are omnivore and love the detritus. Only difference is slight size variations and color/shape of shell.
It is my understanding that the nassarius snails actually are classified in different species list based on size only. They are all actually the same snails, same locations, same benefits for us aquarium keepers just look slightly different. For example, once a vibex reaches +1 inch it is called something different.