Interesting take by Filter Guy on the difference between the assembly line filter and the Motorcraft over the counter OEM.
Based on thread below* Gary Allan (rip) has a somewhat different perspective on the difference between the assembly line OEM filter, and the Motorcraft consumer over the counter OEM. Quoting GA "The assembly line filters are 100% assured to be the absolute cheapest filter that can meet those spec's. It's a bid job and add straight to the cost of the rolling chassis."
And further: "The distinction between OEM assembly line filters and OEM aftermarket filters is that one is a line item on the rolling cost of the chassis coming off the line ..the other falls under normal ROI formulas....."
It's safe to say that both assembly line filter OEM and the Motorcraft have to meet FoMoCo specs. Also that a bid process is involved. But unlike the O'R MicroGard I would say that some kind of longer term agreement is present, and as long as FoMoCo specs and quality are being met, the supplier/maker is not going to be changed willy-nilly.
As to which is better, that may depend on one's definition of better. If as suggested the assembly line filter has a thicker can, than that could be a measure. But, haven't seen many if any complaints about the MC can thickeness. As for efficiency, since we don't know the assembly line spec, and now only know the FL820S spec, don't think anyone can say authoritatively.
All that said, both meeting FoMoCo specs and now especially knowing the FL820S efficiency, I'd have confidence using either filter.
*
Meets or Exceeds OEM Specs