I guess it could be the photo angle or something else, but those impellers dont look the same to me.
open it up and try it, or run it as is.
in the grand scheme of things what is 360 vs 500 gph? those ratings are somewhat skewed anyway, certain temp, voltage, and pump head pressure.
maybe a .3 second difference in clearing the hull of water?
interesting though. take them apart and measure everything.