Canadian English varies from American English in that we use the British spelling of certain words. According to eHow there is a distinctive Canadian accent that is easily recognizable. Apparently Canadians draw out the vowel sounds in words as well as emphasizing them more than Americans. Canadians speak slower, round the "o" and flattening the "a". In addition to the distinctive pronunciation of vowels and certain words there words that are uniquely Canadian terms aka slang that serve as a give away that you are Canadian. Of course the ubiquitous "eh?" and Canadian politeness are two of the most recognizable components of the speach pattern although neither are really part of the Canadian accent but rather distinguishable Canadian teminology.
I'm not convinced I have a Canadian accent but according to others I do and apparently it is very, very noticeable. My husband on the other hand is seldom told he has a Canadian accent but rather he is asked if he is Canadian if he uses certain words. I attribute this difference in dialect being due to my ancestry going back to the first Canadian settlers (French, English) and Aboriginal Canadians while my husband is first generation Canadian on his paternal side and second generation Canadian on his maternal side so had the infuence in his speach patterns from those who's first language was not English.