The two broad categorizations of laborers is skilled (e.g. doctor) and unskilled (e.g. an assembly line worker).
This will increase the wages of skilled workers, but not of unskilled workers.
Skilled workers will be gain proportionally more wealth than unskilled workers.
If a country has an absolutely advantage in both skilled and unskilled workers, but a comparative advantage in unskilled workers, the country will specialize in the good that is intensive in the use of unskilled labor.
The increased returns will go to unskilled workers (they will see their wages increase), even though the country also has an absolute advantage in skilled labor.