Little Joe vs digit

Little Joe and digit both are nouns.

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

As nouns, digit is a hypernym of Little Joe; that is, digit is a word with a broader meaning than Little Joe:

Other hypernyms of Little Joe include figure.

Little Joe (noun)	digit (noun)
the cardinal number that is the sum of three and one	a finger or toe in human beings or corresponding body part in other vertebrates
	one of the elements that collectively form a system of numeration
	the length of breadth of a finger used as a linear measure