US residents can't get a slew of the Norinco designs, due to a ban on import weapons from China back in the late 80s or 90s. So we can't get the M14 copies, the 1911 copies or the AR copies that Marstar sells.
You have a few regulations that are more relaxed than the US. You can have sub 18" barreled shotguns as "restricted" weapons on your PAL, IIRC, whereas in the US they're registered on our NFA list, and require LEO signatures, a $200 tax and relatively extensive paperwork for a US citizen.
Also, you have some rifles that are only on the restricted list (one or two of the Sig 55X series of rifles are not "prohibited" rifles by some oversight of the Canadian government,IIRC), whereas those are prohibited in some US states that have continued bans on assault rifles.
There are some Canadian gun owners with very nice old "prohibited" class collections, who are better off than certain US gunowners.
I'd rather live in Alberta than New Jersey or NYC for gun ownership purposes.