Actual small towns in Ontario have populations of no more than 5000. 50000 is a small city. Relative to its surroundings, Kitchener-Waterloo is a medium-large-sized city. Very few Canadian cities reach the million mark (it used to be only Toronto, but I'm pretty sure Vancouver is there now too, and maybe one or two others).

600k is not a small town in comparison to a 7 million pop capital. I get that your argument is essentially the words are meaningless because theres no strict population density, but by that logic I could call Toronto a small town because its on the same continent as New York.