Full name was Nikon F, Photomic FTn. I own one. Yes, the difference was the viewfinder. The standard Nikon F came with just an optical pentaprism viewfinder and NO meter. The Nikon F, Photomic FTn has the center-weighted meter-equipped viewfinder.

As I recall, there were at least five viewfinders for the Nikon F.

Mine was originally the FTn with 50mm f/1.4. It sold in the USA for $443 list, but few people paid that, unless they were wealthy or uninformed. Discounts of 20% or more were common then.

$443 in 1969 equates to roughly $3,135 in 2020, according to my inflation calculator app. That's why, as a 14-year old in 1969, I bought a Nikkormat FTn with 50mm f/1.4 instead. It was $237.95 at Altman's in Chicago (which equates to roughly $1684 in 2020). I had earned it by selling prints to classmates and the yearbook staff at my school (images made with a borrowed Canon FX).

I inherited the FTn in 1972, when my step-uncle died. He had bought it in Hong Kong, a week before his death. It had half a roll of exposed Ektachrome in it.

After living with about 20 different film cameras and 10 digital cameras over the years, I have to reflect that the Nikon FTn was elegant, rugged as a tank, precise... but awkward to use, and ergonomically challenging and quirky. The Nikon F3, on the other hand, was my favorite 35mm SLR of all time. I have one of those, too. I had two of them at one time. It was all I ever needed in a 35mm film camera.

During my early days in the USAF my camera was a Mamiya Sekor 35mm range finder that I purchased at an AF Exchange at an air base in the upper peninsula of Michigan. In 1971 the AF sent me to Misawa AB, Japan where the BX had a fabulous assortment of cameras. I walked in one day intent on purchasing the popular Asahi Pentax Spotmatic for $125. Next to it was sitting a Nikon FTN with the 50mm f1.4 lens for $192. I still have the FTN. I went digital with the Coolpix 990 (3.3MP) in 2000. My current Nikon is the D750.