We've been home from Canada for a week or more, enough time for impressions to ripen and thoughts to emerge. On this trip we traveled only to the province of Alberta, which Canadians say is the most like the U.S. Take that as a caveat for what follows.
As an American, traveling to Canada, I experience the two countries as very similar. So similar, in fact, that there is virtually zero culture shock. As an experienced traveler, I look for differences and, if I look very carefully, see a few. What amazes me is how few I do see, substantially fewer than there were 30+ years ago when I first started going north.
Canadians focus on the few differences that do exist; they magnify and value them as indicators of their independence. For example, they converted to metric and do business in kilometers and liters. On the other hand, they didn't choose to drive on the left or use 220 volt, 50 cycle power as the rest of the Commonwealth does. So be it.
The difference that most fascinates me is how much the average Canadian knows about the U.S., and how little the average American knows about Canada. It's like when a mouse lies down to sleep alongside an elephant, the mouse sleeps with one eye open, the elephant doesn't. That is, things that happen in the U.S. can really affect life in Canada; things that happen in Canada are much less likely to affect life in the U.S.
However minor the differences, I like Canada a lot - enough to want to visit every 2-3 years during the short but pleasant summers.