Back when the F and its meter heads and the Nikkormat in its various incarnations were both new, the key differences were seen as:
Originally Posted by L Gebhardt
Nikkormat much less expensive.
Nikkormat finder not as nice in several respects; didn't show 100% of the frame, screen wasn't interchangeable, meter couldn't be upgraded as newer/better came out.
Nikkormat shutter/film transport much less durable. F, claimed MTBF 150k shots; 'mat, claimed MTBF, 30k shots.
Nikkormat X sync 1/125, F 1/60.
FWIW, when I had the chance I bought a Nikkormat FTN instead of an F with FTn head. At the 4 Wing RCAF spring, 1970 camera show, Nikon AG wanted all of about $50 more for the F + FTn head than for the 'mat. Two things turned me against the F. At the time, IIRC, I was an E-3; $50 meant a lot. And with the meter prism, the F felt very front-heavy in my hands. I never regretted getting the 'mat.