What is the difference between negrito and negro in Uraquay’s version of Spanish?
It's been explained many times. The former is the diminutive form of the latter. Precisely how diminutives
work depends on context.
Both "negro/negra" and "negrito/negrita" are used non-offensively (as a term of affection, to the extent that parents use it to refer to their children) by Spanish speakers (all over the world). That is beyond question. The phrase "gracias, negrito" in isolation can simply mean "thanks, mate" or "thanks, love" or "thanks, baby".
The problematic aspect of the term has to do with its
origin. It does refer to colour (whether skin colour or even just eye or hair colour) even in its modern use, and some would argue that its modern/current use (which is clearly not
racist) has evolved (like many things) from a past that is anything but unproblematic.
Google it...it's a complex question.
Start with "Jennifer Lopez + negrita".