I have several Bianchi bikes from the 1980s and I noticed the "Bianchi" decals are applied to the tubes differently.
For the 1986 and 1987 models I can feel where the word "Bianchi is raised and you can tell these are some kind of vinyl or plastic decals.

But for my 1983 (or 84?) specialissima the tubes are smooth and you can't feel where the letters start and stop, but the letters do feel a bit different.

For higher end models were the model name and "Bianchi" labels painted on did they just do a much better job?