Babylonian vs Sumerian

Babylonian and Sumerian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Babylonian	Yes	Yes	No	No
Sumerian	Yes	Yes	No	No

As nouns, Sumerian is a hyponym of Babylonian; that is, Sumerian is a word with a more specific, narrower meaning than Babylonian:

Babylonian (noun)	Sumerian (noun)
the ideographic and syllabic writing system in which the ancient Babylonian language was written	a member of a people who inhabited ancient Sumer
an inhabitant of ancient Babylon

Babylonian (adjective)	Sumerian (adjective)
of or relating to the city of Babylon or its people or culture	of or relating to ancient Sumer or its inhabitants