nigga vs Negroid

nigga and Negroid both are nouns.

Word	Noun	Adjective	Verb	Adverb
nigga	Yes	No	No	No
Negroid	Yes	No	No	No

As nouns, Negroid is a hypernym of nigga; that is, Negroid is a word with a broader meaning than nigga:

nigga: (ethnic slur) extremely offensive name for a Black person
Negroid: a person with African ancestry, "Negro" and "Negroid" are archaic and pejorative today

Other hypernyms of nigga include African-American, Black, Negro, Black person, blackamoor.

nigga (noun)	Negroid (noun)
(ethnic slur) extremely offensive name for a Black person	a person with African ancestry, "Negro" and "Negroid" are archaic and pejorative today