Why is it that the part of South American that the Portuguese colonized ended up as one country while the areas in Central and South America colonized by Spain were split into many different countries?

Mentioning previous answers should not discourage more questions, information, or debate.

/u/AD1337 wrote a reply to "Brazil is a huge country. One could easily imagine that over the course of time it would have splintered into 2, 3, or five different countries. What has kept it together?" at https://www.reddit.com/r/AskHistorians/comments/7rr30o/brazil_is_a_huge_country_one_could_easily_imagine/ . They pointed out that there were a couple of attempts to split, but the revolts were ended.

As for Spanish America, you can see /u/yodatsracist answering under "Why did North America split into 3 countries and South America split into 15 though they were colonized similarly?" at https://www.reddit.com/r/AskHistorians/comments/2doi5s/why_did_north_america_split_into_3_countries_and/ (with some bonus notes on North America).

There's also "Why did the Portuguese colonies in South America evolve into a single country (Brazil) whereas the continent's Spanish colonies broke off into nearly a dozen countries?" at https://www.reddit.com/r/AskHistorians/comments/3duadi/why_did_the_portuguese_colonies_in_south_america/ . It's a mismash of different comments, mostly on Portugal and Brazil, some Spanish, a little North America, by too many people to credit.