There are some differences beyond the physical connector.

The electrical standards are very similar, but not exactly the same. You may find that voice quality is degraded when using equipment that's intended for a different country's network.

The Canadian standard ring is different from that in the UK. It's one long ring instead of two short ones. That's not usually a problem, but could cause issues with equipment that's programmed to pick up after a certain number of rings rather than a set time.

Caller ID works differently in Canada compared to the UK. If your machine includes a caller ID feature, that might not work properly or at all. Some equipment is multi-standard and will work on both systems.

Unless it's a particularly elaborate or expensive machine, you'd be better off buying new in Canada.