Yes, bit rate is not the only gauge of picture quality. While I do think there is some difference between streaming and disc, I think even the most ardent videophiles would have a tough time telling which is which in a double-blind test.
I also found the Arrow blu-ray of The Thing to be excessively grainy. And that's a movie that never looked particularly grainy in release prints. Their Robocop 4K also struck me as grainier than I would have expected.