Changes - Vandersteen 1, 1B, 1C

Could someone tell me what changes were made to distinguish these three different speakers? Also, does anyone have a digital version (PDF) of the original 1C manual?

Manuals are available on the Vandersteen website.
I found the two-page flier about the speakers, but not the manual.
The front page of the Vandersteen website has a section Online Manuals PDF. It's the second box on the page.
The 1C has a metal dome tweeter while the 1B has a silk dome. I'm most likely going to buy the 1c b/c it does not have any negative reviews on