I bought and installed an AutoZone Duralast Gold starter (NEW) into my '96 Saturn on Saturday. The factory unit that I removed from the car was a Valeo unit that was "Made in France." The starter that came in the Duralast Gold box was also a Valeo brand, but Made in Poland. It had an updated design that did not require the dust shield (N/A to me anyway) and had a different solenoid design. I was essentially sold the dealership part for about 1/2 price...$149.99 from AutoZone vs. nearly $300 from the Saturn dealership.
I guess that for some low volume parts, it doesn't make financial sense for a vendor to tool their assembly line to make the component, so they just purchase it from a different supplier. Sometimes you get lucky!