With respect to universities in Canada, only one has a reputation of any worth outside the country: the University of Toronto. In keeping with our slightly more socialistic social contract, you will find that university is cheaper for mediocre students than it is in the US and pricier for good students than in the US.
Like the US, Canada is not monolithic and has many regional variations with respect to climate, culture and everything else you might imagine. While, in the past, Canada has been pretty politically similar to the US, we have diverged a little more in recent years not so much in areas of policy but in terms of how we talk about ourselves. The Bush administration is more disliked in Canada than Nixon's was and this rubs off a bit in an unprecedented level of general US-bashing even in relatively conservative areas of the country. If you're a highly political Republican, therefore, you might find yourself having to be a little quiet about it in social situations in a way that has never been true here before.
You'll find Canadians are, in many respects, more into US popular culture than Americans are. Racial politics are a little different here than in the US -- most of Canada's black population are recent (since the 1960s) immigrants from the Carribean and are concentrated in Quebec and Ontario. And, outside of Quebec, there are few Hispanic people. West and north of Ontario, the main racial minority are aboriginal people, although they are outnumbered by Chinese and South Asian (Indian subcontinent) people in the cities of BC and Alberta. Issues that might be understood as racial in the US are often understood by Canadians as being about ethnicity or culture; our national multicultural policy is about twenty years older and very different from that of the US.
If I had to pick one state to compare Canada to, I'd say we're like California, minus the hispanic people -- liberal, regionally diffuse, highly urban and much enamoured of US cultural exports.
EDIT:
When coming up to visit colleges, avoid the area from Edmonton to Quebec City during the winter (except maybe the area along Lakes Erie and Ontario) during the winter if you can. The area from Calgary to Victoria and the three Maritime provinces aren't too bad in the winter.
And, Greyhound buses in Canada, while bad, are nowhere near as bad as those in the US. Don't take the train unless you are in Quebec or Ontario (that's where all the rail subsidies go) or are independently wealthy.