Yes I think you're right 3 versions, depending on mount (possibly):
In the 14mm f2.8 (I'm not including the newer more expensive f2.4)., there was/is .....
1. The Original -
Samyang 14 mm f/2.8 IF ED MC Aspherical
>>>>>>>>>>
https://www.lenstip.com/index.html?t...wu&test_ob=200
2. UMC version - Optical & Coating Improvement over original,
without AE
Samyang 14 mm f/2.8 ED AS IF UMC
>>>>>>>>>>
https://www.lenstip.com/index.html?t...wu&test_ob=239
3. UMC Version + AE /Comms with camera
Same as above but with camera AE/Comms
The UMC designated lens should be preferable given the improved coating and optics mentioned in the reviews above and borne out in the test results provided., refer especially to the resolution and coma test pages of each of the 2 reviews (pages 4 & 7) and you will see a clear and definite advance on the original version, which the reviewer if I remember correctly, in conjunction with other reviews show that it can better the 14-24 Nikkor, 14mm Canon and the 15mm Irix re coma and res at full aperture.
Best
JA