I'd hope the difference could be seen in the polish on the edge? Might try a few passes with a softer metal (copper, brass, nickel, etc.), and see which hones put a higher polish on. Use a magnifier under bright light, to examine the scratches left by each, on the metal. Examine the metal trace left on the hones; I'd assume the traces would be lighter on the finer hones. If the hones are too dirty, clean them thoroughly (use Comet, Ajax or Bar Keeper's Friend). Finer ceramic hones will usually clean up more easily (leaving less metal trace behind), so you might see a difference there too. One simple test I'd try in this regard, is to rub a penny or other soft metal on each, then use a pencil eraser to see which streaks rub off more easily (again, the finer ones should clean up easier, as they presumably remove less metal per pass).
{ Edited to add: The finer hones should feel noticeably slicker when a blade is drawn across them (assuming they're CLEAN; if not, clean them first). }
If, after all that, you still can't tell the difference, I'd think the UF hones probably weren't doing you much good anyway.