IV vs Little Joe

IV and Little Joe both are nouns.

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

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

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

IV (noun)	Little Joe (noun)
administration of nutrients through a vein	the cardinal number that is the sum of three and one
the cardinal number that is the sum of three and one