Yes, A1200HDs are identical to the regular A1200s except they were fitted with a hard drive at the factory. Many dealers added hard drives to basic A1200s and thus, their machines don't have an official HD designation.
The Amiga Technologies A1200s have a different floppy configuration - they use a modified PC floppy drive since they couldn't source enough Amiga Chinon drives at the time of manufacture. The motherboards are slightly different to make use of them, but they can be modified to be identical to Commodore's boards. Amiga Technologies 1200s also shipped with OS3.1 by default.
As for the Vesalia offer, why don't you email them and find out? ;-)
