I think that in Canada, you aren't allowed to ask and/or are not allowed to answer that question during the application process.
Versus in the US, you are allowed to ask, you may answer, but are not required to.
It's just a "just don't talk about it" kinda thing rather than a "not allowed" kinda thing. It's just to prevent any prejudice that might happen and to ensure gender equality and stuff at least in the application process.
Versus in the US, you are allowed to ask, you may answer, but are not required to.