The real difference between (Southern) Ontario and the American Midwest is not actually a difference of how much violence occurred but really of HOW the violence occurred. The inhabitants of Southern Ontario at the time of contact were the Wendat (Huron) and Atirhagenrat (Neutral) Confederacies. There was a quite intense violent period called the 'Beaver Wars' in which these Confederacies were pushed out by the Haudenosaunee (Iroquois). The Haudenosaunee were in turn displaced by the French fur traders who were in turn displaced by the British. By the time of the American War of Independence Ontario's equivalent of the Indian Wars had already happened.
Not that there wasn't a signifcant difference in policy between Britain/Canada and the US, just that the differnece wasn't necessarily violence vs no violence. The difference was that the US largely used their own troops to drive out Natives while the British just got their Native allies to do most of the violence for them.