Funny you mention that as i wasn't commenting on why they were different.
If you look here the Canadian Senate released a report to "explain" the price gap.
http://www.parl.gc.ca/Content/...
The problem is the report fails to point the finger at what is probably the single greatest reason for the price gap (the government).
Buy a pair of kids socks in most US states and you will find they are tax exempt.
Not so here, the government wants its 13% tax on that purchase (Ontario, we have HST)
Buy a winter coat in most states and only pay taxes on the "non-exempt" portion (assuming your coat is over the non-exempt amount).
Buy a winter coat in Canada, and it is 100% taxable, clearly they have no issues taxing "required" things as well.
Heck, they even tax food here (there is a very small list of "exempt" items, but only what they determine is "essential").