The difference that can be seen between the English and the Brobdingnagians is that the English reward nobility, while the Brobdingnagians reward knowledge.
This fact is made evident because when Gulliver speaks of England, he focuses on the English Parliament being composed of "persons of the noblest blood, and of the most ancient and ample patrimonies"; while when the King speaks of Broddingnag, he wonders about the "methods [...] used to cultivate the minds and bodies of [their] young nobility" while wondering at the same time "What course was taken to supply that assembly when any noble family became extinct?"