seven vs digit

seven and digit both are nouns.

Word	Noun	Adjective	Verb	Adverb
seven	Yes	Yes	No	No
digit	Yes	No	No	No

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

Other hypernyms of seven include figure.

seven (noun)	digit (noun)
one of four playing cards in a deck with seven pips on the face	a finger or toe in human beings or corresponding body part in other vertebrates
the cardinal number that is the sum of six and one	one of the elements that collectively form a system of numeration
	the length of breadth of a finger used as a linear measure

seven (adjective)	digit (adjective)
being one more than six