This guy goes on and an about the 201, lots of interesting information. For the most part the Singer factories were very good at producing identical machines and parts where ever their factories were situated. There's usually sub model number where there is any difference. Regarding the 201, I suppose most were fitted with motor and light but I regularly see treadle and hand cranks. Treadle and hand cranks were much more common than I previously assumed, still being made way into the 1950s. I have seen two types of decor on the chrome plates of the cast iron version; an art nouveu pattern which I like a lot, and around 1950, or just before they introduced a pin striped version. Decals might have differed a bit too over the years, but always rather simple gold and black, nothing elaborate compared to earlier models.
As the piece on the 201 says; the last 201s were aluminum in stead of the heavy cast iron, it was given a different look, more angular and modern looking for the time. The internal parts are as far as I know inter changeable. My 201 is from 1950, heavy cast iron, just a few years later they were all aluminum, and the last ones came in a two tone beige and brown. This should account for the different looks of the 201.