Diamond uses the story of Pizarro's conquest of the Inca to demonstrate the differences between American Indian civilizations and the European civilizations that conquered them. Both the Inca and the Spanish were highly stratified, complex societies, but Spain developed maritime technology, superior weapons, and writing systems, whereas the Inca did not. Essentially Diamond argues that certain advantages in Eurasia privileged the civilizations that developed there, including more variety in domesticated crops and especially domesticable animals. Of the fourteen animals first domesticated by humans, none lived in North America and only one (the llama/alpaca) lived in South America.
This very unequal distribution of wild ancestral species among the continents became an important reason why Eurasians, rather than peoples of other continents, were the ones to end up with guns, germs, and steel.
Another major difference that led to the development of technologies at a more rapid pace had to do with geography. Europe and Asia were oriented along an east-west axis that made it easier for agricultural practices to spread because societies, being on similar latitudes, had similar soil types and climates:
Localities distributed east and west of each other at the same latitude share exactly the same day length and its seasonal variations. To a lesser degree, they also...share similar diseases, regimes of temperature and rainfall, and habitats or biomes...Portugal, northern Iran, and Japan, all located at about the same latitude...are more similar to each other in climate than each is to a location lying even a mere 1,000 miles due south.
North and South America were oriented along a north-south axis, which meant that food production technologies and techniques spread more slowly. There were significant differences in climate between Central America, for example, and the American Southeast, because they lay on different latitudes. So crops had to undergo significant mutations, which takes time, to spread to these different climes.