Well I have thought about this quite a bit in the past. This is my personal Idea. When the Spanish arrive in Latin america they do create the Caste system and there is not a huge pressure for amerindians to become European. The Spanish respect the lands of tribes that allinged themselves with them and create basically Indian territories. The Spanish deport both Moriscos and Jews their aswell so that is abiut 750k people. The Spanish encourage many more Spaniards to Immigrate and also encourage other Europeans to migrate. They don't brutally supress their colonies and treat them better, much more like how the English treated their colonies. After independence they industrialize and accept larger amounts of European migration. Gor Brazil probably they would need to abolish slavery sooner and industrialize and accept more european migrants, also it would be helpful for the portugese to get other europeans to populate Brazil with them early on.