My OEM Yokohama Radial 360 (aka Y360?) is a P205/75R14 which aligns with their offerings depending on model/options as you mentioned. My VIN plate shows a P195/75R14 - I would think my spare would match the VIN plate. Is it possible the spare was at some point changed to an identical model Yokohama with a larger width to a 205? Sure. Knowing the full history and ownership of the truck, I doubt it and think this is how it was sold new. Maybe they are all this way, I'm sure someone smarter than me on the subject can chime in or check their truck VIN tag and factory spare.
That mfr./VIN plate is just stating the parameters used to determine the GAWR (Gross Axle Weight Rating), in this case using the base-spec tire option. Using a different tire size/spec could slightly alter the GAWR/GVWR -- e.g., a larger tire on the same wheel would weigh more and may be less stable (due to a taller sidewall being more flexible), or an LT tire of the same size with a higher load rating would weigh more (due to more robust construction), so those may reduce the max. payload capacity (= GVWR minus curb weight).