Our World in Data on comparative advantage

To see the difference between comparative and absolute advantage, consider a commercial aviation pilot and a baker.  Suppose the pilot is an excellent chef, and she can bake just as well, or even better than the baker.  In this case, the pilot has an absolute advantage in both tasks.  Yet the baker probably has a comparative advantage in baking, because the opportunity cost of baking is much higher for the pilot.

At the individual level, comparative advantage explains why you might want to delegate tasks to someone else, even if you can do those tasks better and faster than them.  This may sound counterintuitive, but it is not: If you are good at many things, it means that investing time in one task has a high opportunity cost, because you are not doing the other amazing things you could be doing with your time and resources.  So, at least from an efficiency point of view, you should specialize on what you are best at, and delegate the rest. 

The same logic applies to countries.  Broadly speaking, the principle of comparative advantage postulates that all nations can gain from trade if each specializes in producing what they are relatively more efficient at producing, and imports the rest: “do what you do best, import the rest.” 

~ "Trade and Globalization," Our World in Data, 2014

(Look under subtitle, "Theory: What is 'comparative advantage' and why does it matter to understand trade?.")