FFXDF is the over-the-counter ticker in US markets; FIH.U is the ticker on the Toronto exchange (TSE). In both cases, they are in US dollars, but the FFXDF trades very infrequently and you can get some wonky prices. In principle, they should have the same value. But you are probably better off to buy the shares on the Toronto exchange if that is possible with your broker, and if not, perhaps put in a limit order for FFXDF with a price that closely matches the value you see for FIH.U.
thanks, dartmonkey
now it makes sense. I was under the impression that FIH.U trades in CADs.