Group ride in Canada uses a tethered phone and requires mobile data. Basically useless outside coverage area, but works well within.
In the USA, the basic model of the tread works the same with a phone. The upgraded model with the 2 way radio uses radio communication as described above. As far as I can tell the head units are the same, the radio hardware is actually part of the mount.
The radio version is not available on the Canadian website, but I suppose it would be possible to get an american model shipped to Canada.
I have 2 seasons with a tread and I'm pretty happy with it. Its not perfect, but would recommend. Coming from a navigation oriented company, there are many useful features if you put in the effort to learn and do the programming. The maps overall aren't nearly as detailed for Canada though. Their tech line is very responsive and helpful. They will literally spend an hour on the phone one-on-one to help with problems.