One of the largest distinctions between American and Canadian pronunciations of words is what I understand is called "Canadian Raising". This is the alteration of the first vowel sound of a diphthong when the next consonant is a 'hard' one.
The distinction is made to some extent by most Americans I know too; the intensity of difference, and frequency of occurrence, goes down the further south the speaker lives (roughly speaking).
At a guess, I'd enumerate "hard" consonants as ch, f, k (including hard c and q), p, sibilant s, and t. Some consonants seem never to follow these diphthongs in EnglishLanguage at all! Or at least I can't think of examples, so I can't classify them as "hard" or "soft" for purposes of this rule.
The first vowel sound is "raised" (although I have no idea in what sense the linguists mean the term; if anything, I'd think of the sound as "lowered") in this context.
The application is actually very consistent. One thing that obfuscates matters is that EnglishLanguage speakers are probably not used to thinking of their long i sound as a diphthong.
I think it is the difficulty in getting the second sound right that results in the common stereotype of the Canadian who speaks of being "oot and aboot" (see AmericanCulturalAssumption, CanadianCulturalAssumption). Interestingly, though, I once tried to teach some American high school students the differences and get them to pronounce "light" in such a way that they'd blend in, and they couldn't get the hang of it. My experience is that my friends "up here" are a lot more versatile when it comes to picking up new vowel sounds. In high school, I found myself in situations where I was in mixed company with non-immigrant Canadians, non-immigrant Americans and immigrants, typically Asians; and found that I and my Canadian peers had a much easier time of pronouncing the foreign names like "Liu". As well, I can "fit in" with an American "accent" pretty well (although I'll probably be caught for saying "eh" instead of "huh", or other such details), but I can spot an American visitor (except perhaps those from border states or the Eastern Seaboard) to Toronto the first time s/he wants "ice" in a drink.
-- KarlKnechtel
I'm francophone so I'm used to thinking of long-i as a diphthong, and being bewildered by the notion that it isn't. Anyways, I learned English in Toronto but I don't notice the distinctions you mention above in my speech. -- RK