Being nearby, I've been places within Ontario quite a lot - though not very recently. I never had any feeling I was in the US. Everything always looked and felt a bit "off" and unpredictable. The laws, culture, and even retail commerce are different as is the way people act toward one another. Not hostile, but a bit cold with a constrained sense of humor. Almost a general sense of depression and touchiness. Business dealings were often dicey, and one had to take care not to offend.
This wasn't just in Toronto, so it wasn't "big city" coolness. I saw it in cops, fishing guides, farmers, and itinerant farmhands well outside the city too. Ontario treated its domestic farm workers much like foreign migrant workers here. Probably a holdover of French Colonial culture from early times there.
It's just different, as one should expect.