What was common in the structure of the Portuguese and Spanish colonial empires? How were they different?

Both the Spanish and Portuguese colonial empires had colonies in South America, the islands of the Atlantic Ocean, as well as the North and West coasts of Africa in common.
Both countries were among the main maritime powers of the time. Only Portugal fully controlled the Indian Ocean and the trade route for the supply of silk and spices to Europe, while Spain controlled the sea route to America and the outlet from the Mediterranean to the Atlantic.
Among the differences, it is also worth highlighting the fact that slavery was widespread in Portugal.