Nilo-Saharan vs Saharan

Nilo-Saharan and Saharan both are nouns.

Word	Noun	Adjective	Verb	Adverb
Nilo-Saharan	Yes	No	No	No
Saharan	Yes	Yes	No	No

As nouns, Saharan is a hyponym of Nilo-Saharan; that is, Saharan is a word with a more specific, narrower meaning than Nilo-Saharan:

Nilo-Saharan: a family of East African languages spoken by Nilotic peoples from the Sahara south to Kenya and Tanzania
Saharan: a Nilo-Saharan language spoken in parts of Chad

Other hyponyms of Nilo-Saharan include Chari-Nile, Saharan language, Songhai, Songhai language.

Nilo-Saharan (noun)	Saharan (noun)
a family of East African languages spoken by Nilotic peoples from the Sahara south to Kenya and Tanzania	a Nilo-Saharan language spoken in parts of Chad

Nilo-Saharan (adjective)	Saharan (adjective)
	of or relating to or located in the Sahara Desert