My impression is that the earliest version as you describe with a black and silver label, was nicely buffed just like the satndard model but then the alloy was also clear anodized. Also, the pivot bolts used were tightened with an Allen wrench (hex-key) while the standard model still used hex head bolts. The forged alloy parts were likely the same.

This at least holds true for the GC version which I recall from perhaps the early 1980s. Then by maybe 1986 or possibly earlier, the NGC (New Gran Compe) models were given a more streamlined look with no labels on the front and even included "wheel guide" finger holds - similar to what was used to help set up sidepull brake pads at the rim. The later NGC model arms also had only a shorter reach making them best suited to later road bike framesets with tighter tire clearances.

I think I have seen a 1980s catalogue posted somewhere on the internet which may help illustrate all of this better, but I can't seem to locate the source right now...