Susan - I think I understand it now.

GTU's chart looks a lot like the Canadian version of CEF (CEF/A.to) which looks like gold in Canadian dollars. The American version of CEF looks like gold in US dollars. The only explanation is that GTU is currency hedged. Today the Loonie dropped, which explains the move in GTU.

Bottom line - if you're bullish on gold and you think the Loonie will gain against the Greenback, buy CEF, if you think the opposite, buy GTU.