Production costs in one nation may be lower than in another nation for every item produced in either nation. But the people of these respective nations may still find it profitable to trade with one another. It is often thought that only nations like Great Britain or other maritime nations benefit by trade, simply because there are so many things they do not produce domestically. Consumption is the sole purpose of production. Adam Smith explained this nearly 200 years ago.
Production is to supply consumers' wants.
Naturally, some of these things happen as a by-product of production and trade, but that should not be the objective. If an individual in this country wanted to trade some of his own property for something offered by a Russian citizen, we would think little about it, knowing that each party to the trade considered he was better off than before. But if government enters one or both sides of such a trade, there is often the suspicion, sometimes justified, that one party is seeking a military or political advantage. Foreign trade appears complicated because it often takes an indirect or roundabout route through several nations. In addition, monies of several nations with complex exchange rates are usually involved.