Was ist der Unterschied zwischen A Canadian und A Canadian national und A Canadian person ?Du kannst auch einfach Beispielsätze geben.

They are all roughly equivalent. In normal conversation, one would typically just say "A Canadian." For example,

"Even when angry at you, a Canadian would still be ridiculously polite."

"A Canadian national" is emphasizing the geopolitical aspect. For example, "Three Canadian nationals are currently detained in Chinese custody." This is what you might see on the news. It is emphasizing the geopolitical aspect of their nationality. In the first example I gave, it would be weird to say "...a Canadian national would still be ridiculously polite."

A Canadian person sounds kind of weird, I probably wouldn't say that, as it is redundant.