kz250....d/d1/d2?

OK, new member, did a search and to be honest, gave up before i went thru all 60 something threads, so sorry if this has been addressed before .
I have a 1980 kz250 that I've been playing around with. The manufacture date is Feb of 80. The data plate just says KZ250D.
When doing searches for parts all the listings are for D1 or D2, so my question is.....
A.Is a D1 the same as a D and everybody just adds the "1" so differentiate it from a D2, or is there actually a difference between a "D" and a "D1"
B. If there is a difference between the "D" and "D1", whats the main difference (so I might be able to make an educated guess as to what parts are likely to be interchangeable)
Thanks in advance for any help

I owned a 1981 kz250 D2 the 1980 is called a D1. The difference is that the D2 had factory electronic ignitIon and the previous bikes ran points. Maybe some other minor changes but I recall the supplement in the shop manual for the different ignition in the 81's.

The manufacture date in Feb of 80 should make it a 1980 D1..
You can poke around the diagrams at partzilla to see what's what.

Cool,thanks for the help guys.