Americans parody Canadians by saying "aboot" (real clever) and some Canadians claim they don't say it.
But they do. It's not really the hard oo sound of "boot," but it's not the ow sound of "towel," either. It's a sound somewhere between ow and oo that I can't pronounce, but wish I could. It's distinctively Canadian. Even Canadians who have lived and worked in the US most of their lives will have just the slightest hint of "aboot" in their speech. I always smile when I hear it.
Many Americans don't know that other, everyday words are pronounced differently north of the 49th parallel.
In the US, "again" and "against" have a vowel sound like "fence". In Canada, in those words, you hear the word "gain".
In the US, "been" - as in, I've been working on the railroad - rhymes with gin. In Canada, "been" has the same sound as "bean".
There's project - Americans say prah-ject, Canadians pro-ject - and process, same distinction. In each case, Canadians pronounced the "pro" to rhyme with "toe".
On an episode of Corner Gas, Mark McKinney, playing an anti-stereotype of a mild-mannered American, asks if the folks in Dog River are bilingual - pronounced with four syllables: bi-ling-you-al. In the US, that word has three syllables: bi-lean-gwal. Dead giveaway.