Well, you might want to read this series I wrote on the different city-states of Essos. But the short version is: the Free Cities are (mostly) republican city-states rather than monarchies or feudal aristocracies, their economies are based on finance, commerce, and advanced manufacturing rather than subsistence farming; in terms of technology, Myr is producing lenses, telescopes, and advanced crossbows; Braavos uses the assembly line and interchangeable parts in the manufacture of ships and uses double-entry bookkeeping in its finance; Qohor has advanced metallurgy. Culturally, Braavos has Elizabethan theater for crying out loud!