The fact is, the meaning of words can entirely flip over time, and meaning is informed by the context in which the word is spoken. The evolution of "nigga" is such that within the right context its meaning is neutral or positive. It is essentially a reclaimation a word that was used to denigrate. The problem is that there are still people who would use the "nigger" version as an insult. These are two similar sounding words with two entirely different meanings. Which one is intended is largely determined by context. The usual assumption is that anyone who is not black (or someone where a close friendship is already established) is intending it in the negative way. But there are plenty of blacks who don't like any version of the word at all.
(A black male who occasionally uses the word)