There's definitely more to be said about this particular question, but /u/lord_mayor_of_reddit's answer to the question 'What made English colonies in Canada different from the "thirteen colonies"?' does provide some explanation of the early differences between Canadian colonies, and the colonies that would make up the USA.

Hi, here are a few responses citing other factors:

• Why has Canada's population remained so low?

• Why is Canada's population so small for its size ?

• Why is there such a big population difference between Canada and USA?