The AR-15 is not an assault rifle. "Assault weapon" is not the same thing as "assault rifle". The latter is a technical military term for a class of selective fire (both semi-automatic and fully automatic) rifles such as the M-16. I suspect that assault rifles have long been prohibited for general ownership in Canada, as they are in the United States. "Assault weapon" is a bull **** made up term with no consistent definition, which often depends on the presence of certain cosmetic features to define it.
Guns designed specifically to kill people, guns that mimic them via cosmetic features, and guns that people mistake for them -- why would the Canadian public need any of these things? So I'd consider your distinction to be one without a difference.