So I’m Korean but have a Canadian passport, does that make me Korean or Canadian? ?

If you went to local Korean school, you would be just Korean with a Canadian passport/Canadian citizenship.

Since you attend international school, you are a Canadian-Korean.

Korean Canadians are Canadian citizens/residents with Korean ancestry and you are apparently not one of them.

You are a Canadian Korean - a Korean resident with Canadian ancestry. 

If you are a citizen of Korea, you’re Korean. If you are a citizen of Korea but live in Canada (and are also a citizen there), you’re Korean Canadian. If you are a citizen of both then same answer. If your citizenship says Korean, then Korean. Doesn’t matter about your passport. 

probably both. look in your passport(s). If it says "nationality: Korean" you are LEGALLY Korean. If it says "nationality: Canadian"  you are LEGALLY Canadian.

If you were raised in Korean that makes you ETHNICALLY Korean. If you were raised in English or French you are ETHNICALLY Canadian. You can be both if raised bilingually

There's no such thing as "genetically" Korean or any other nationality/ethnicity

I find your story very difficult to believe. The fact that you were compelled to post anonymously is also a dead giveaway that you're lying. Children born in Korea to Korean parents are Korean citizens. It wouldn't matter if your mother had spent 100 years in Canada - to get there from Korea you would have needed a passport. Having never been to Canada before you would have only been eligible for a Korean passport. If both of your parents were ethnically Korean, you wouldn't be asking whether or not you ought to be considered Korean. All overseas Koreans raising kids abroad bring their kids up with Korean language and culture being part of their daily lives. This was very pisspoor trolling. 

While in Korea you are a 100% Citizen of Korea.

While in Canada you are 100% Canadian Citizen.

You were born a Canadian Citizen as your mother was a Canadian citizen at the time of your birth.

Call yourself whatever you think is appropriate for the situation.

You are not left side Korean and right half Canadian. You do not have Canadian feet and Korean hands.

Curious is your mother still a Korean Citizen or Canadian only?

When a Korean national becomes a citizen of another country, that individual is no longer a Korean citizen effective on the date recorded on their Certificate of Naturalization.  The individual must personally file renunciation documents, called “**** Jeok Sang Shil Shin Go,” to the Korean government reporting the change of citizenship.  If the individual does not file the necessary documents, it will appear on Korean Family Registry documents as if this person is still a Korean national.

However, failure to file does not mean that this person is still a Korean citizen or has acquired dual citizenship.

The details differ on if you are Male child or female child.

Male nationals of the Republic of Korea have military duties in accordance with the Constitution and Military Service Law. Males with multiple citizenship must choose their nationality by the end of March of the year he turns 18. If he fails to do so in time, he will be obligated to serve.

For you to have a Canadian passport, you would have to be a Canadian citizen.  I assume that during the time your mother lived in Canada she became a citizen.  You got your citizenship through her.

You would be a Canadian citizen of Korean descendant who lives in Korea.  "Legally" you are a Canadian.  "Genetically" you are Korean.

If you were to relocate to Canada, you still be a Canadian citizen of Korean descendant.

I am an American citizen.  I have always lived in America.  But my parents were of German descendent.  So I would be an American citizen of German descent.  Even though none of my relative have lived in German for the last four generations.