Overseas means related to/ on another continent. You have to cross the sea.
International is related to/ in another country.
So if you live in north USA 5miles from the border, and own a company that also has one bureau in south Canada, 10 miles away, then that is an International company. But the other bureau is _not_ overseas. If you then open a third bureau in Paris, France, then that bureau is indeed overseas.
Overseas and international are equal if you live in Australia. Because there is no second nation on that continent.
International means when something is existing, occurring, or carried on between two or more nations and overseas means abroad, in or to another country. So no they don't mean the same thing.
I work at the airport. & domestic is obv in your country.. U.S. international is another country which is also overseas. So I think they kinda do have the same meaning.
iternational means btw two or more countries overseas means btw an ocean