The difference is that the MAJORITY of Europeans, Asians and African people come here legally or are truly refugees and then their status changes
Exactly. That is actually the answer to the original post. The United Status enforces the law really only at the border or within 100 miles of the border. Immigration agents are not really combing the streets looking of illegals.
So because they only apprehend people at the border, in this case the southern border, it's normal that the detainees will be from Central America.
Illegal immigrants who are white, typically arrive via plane, and have a visa that let's them into the country, and then end up staying illegally. As far as Canadians, same thing. They don't need a visa to get it, so they just get in and end up staying illegally.