Correct, there are two variants of the FM. The original version separated the meter switching (wind lever standoff) from the release lock (knurled collar around the release). This proved a clumsy arrangement when the motor (then the MD-11) was used. It was too easy to leave the body release unlocked preventing motor operation.
When Nikon introduced the FE, they moved the release lock to the wind lever. Now the meter switching and motor drive switch over were unified. Wind lever out, the body turned the meter on, unlocked the release and allowed manual wind. Lever in, the body locked its release and turned off the meter allowing the motor to turn on the meter, release the shutter, and wind. About 6 months later (in the US at least), the FM bodies began arriving with the release lock matching the FE.