Little Joe vs tetrad

Little Joe and tetrad both are nouns.

Word	Noun	Adjective	Verb	Adverb
Little Joe	Yes	No	No	No
tetrad	Yes	No	No	No

As nouns, Little Joe and tetrad are synonyms defined as:

Little Joe and tetrad: the cardinal number that is the sum of three and one

Other synonyms of Little Joe include 4, four, foursome, IV, quadruplet, quartet, quatern, quaternary, quaternion, quaternity.

Little Joe (noun)	tetrad (noun)
the cardinal number that is the sum of three and one	the cardinal number that is the sum of three and one