78 KZ650 Model Designations

I have a 78 kz650b2a. Does anyone happen to know what differences there are between the B the B2 and the B2a? From outward appearances the seem identical.

I think all the A designations were California emmisions compliant.

Going by the serial numbers it looks like B2 is the first batch of 1978 models, B2A is late production 1978. I think that's the difference in them.