In this book, Diamond continually emphasizes the fact that geography is supremely important. Therefore, it is not surprising that Diamond says geography caused the differences that you mention in this question. Geography made agriculture less possible in the Americas. There were fewer kinds of domesticable plants and the staple grain (corn) was lower in protein than Eurasian grains. There were not large animals that could be domesticated. It was difficult for any crops to spread along the north-south axis. For all of these reasons, agriculture remained less developed in the Americas. With less developed agriculture, the Americas were also less able to develop the other things that you mention in this question because agriculture leads to the development of those things.