If you're asking about the modern Brass drum vs. a modern BB (seems things have been sidetracked to a discussion about vintage Supers, which are a much different animal) I don't think there is much of a difference. Both drums are nickel plated but the final layer of plating is different. One gets a translucent layer a chrome which protects the shiny nickel (which is actually the shiny surface you see) from tarnishing and gives it a bluish hue and the other gets an equally thin layer of chrome that has been altered to create the dark coloration. I don't see how this slight difference in two similar exterior coatings that are only a few molecules thick would have any great effect on the sound of a drum.
I know from experience that not all Supra drums sound the same even though they were made exactly the same and I'd guess that is the reason for the difference you noted between your drum and the black beauty you tried. I don't own either of these drums myself (I do have a COB Super) but from what I can see the only difference in two drum models made at roughly the same time would be the coloration of that very thin layer of chrome that each wears.