Well, there's a few reasons.

Firstly, Canada had a large French Catholic population who although distrustful of the Anglican (Episcopal) majority in Britain and the English speaking part of Canada at the time, they had managed to live peaceably with them for some time and had seen growth during that period. Many of the Revolutionaries in the US were from Boston and New England, known for its Puritanical and anti-catholic leanings - thus they supported the British as the "known evil" who at least allowed them religious freedom; which they doubted could be said of the radical protestants who broadly backed separation with Britain.

Secondly, the US made an ill judged attempt to invade Canada in 1775, assuming the Canadians would just join them. Thus many Canadians who mightve been open to being talked into union with the US opted not to and fought with the British because even if the U.S. soldiers marching north claimed to bring liberty, they were still an uninvited invading army.

Thirdly, Canada was broadly stable post revolution thanks to a goodly number of Loyalist refugees fleeing the new U.S. for fear of persecution to settle in British Canada, these Tories helped bolster Loyalist sentiment in Canada.

Fourthly, Britain devolved a lot of Government onto Canada, giving it a parliament of its own by the mid 19th century meaning they were effectively self governing early on, simply maintaining a cultural and patriotic link to Britain by the end of the 19th century.

You could go on, but Canada just saw no urgency for independence or separation from a people that many still kept up family ties and correspondence across the Atlantic and if anything felt the U.S. threatened it's liberty more than Britain.

In short, the Canadians were treated better. The Stamp Act was only applied to the American colonies, as were the Townshend Acts. The British needed to get funding for the defense of the colonies and get reimbursed for the Seven Years War, so they enacted taxes. Someone can correct me if I'm wrong, but it seems that Canada didn't require as much effort to defend.

By the time the Americans actually wanted to separate from Britain, there had been unrest for many years. The colonists weren't happy with a lot of things, including "taxation without representation" and the events of British cruelty like the Boston Massacre, which had actually been hyped up quite a bit to make the British seem like tyrants. Simply, these things didn't happen in Canada. In addition, during the 1780s most British loyalists living in the colonies emigrated to Canada because they didn't want to separate from the crown.

Source: Made In America by Bill Bryson and information from my class. I guess here's my textbook