Yes, what does Canada offer that the UK doesn't? Same language, both have a Queen both have a functional government that mostly respects other peoples rights.
The US has a great ecosystem for start-ups. Does Canada?
If you're from another commonwealth country it's a lot easier to migrate to Canada than it is the USA. Regarding what could be more attractive than the UK: there's more open space, cheaper housing, better schools, mountains, etc.
Why would I want to do a start-up in Canada, rather than say the UK or Germany or Chile?