The difference is the type of switches, there's a whole
thread for that. The /r/mechanicalkeyboards subreddit is another good resource.
The answer of which switch is best is totally personally preference. If you have a store nearby that stocks them at all, it's really worth a trip to touch and feel. The two main differences between switches are how much force it takes to press them and what type of tactile "bump" the switch makes when it presses.
Good news for you in Canada is that NCIX has a fairly extensive mechanical keyboard selection, so you should be able to get something that works for you there and not get taken on shipping, etc.
Dont' worry too much about price and get what you want, IMO. These things last. I have an MX brown board that I love, but I wish I'd dropped the extra $30-40 for clears (which I might still do at some point).