The whole thing is a mess. Cherry Corp. gradually replaced molds and changed some materials. There are even keyboards with different switches of the same kind. In addition, there are heavily worn switches... and poorly stored keyboards. Lube applied in the manufacturing process may come into play as well, I guess.
Most discussions are about MX Black, there's something about MX Blue (see Dark Blue and Navy Blue), but old browns/clears are quite poorly documented AFAIK (I can't tell, whether the few mentions are mostly about design, or break-in), not to start with rare kinds of MX switches.
I've inspected '91 blues, and they were visually different from modern blues, neither in color, nor logo though—rather springs and consistently different texture on plastic housings. I couldn't tell any difference in feel in a blind test with various switch parts swapped. Others may have different experience; in particular, I've read about significant difference in sound.
Blacks are tricky. There are Nixdorfs, some others know more about them. Then there are blacks from vintage Cherry keyboards, such as early G80-1000HA*; these are consistently very smooth across the board from what I've seen. I did some blind tests as well, when I had access to some, and could easily distinguish them from modern and modern heavily-worn switches. Springs were visually different from the newer ones, but the feel was determined solely by housings (well, I couldn't tell the difference with only other parts swapped). Apart from these, there are plenty of blacks harvested from Wyse boards like yours. The problem with them is that they're hit-or-miss. I've had some very gritty and some very smooth ones, even from one batch, and even on a single barely used keyboard.