grapefruit vs citrus

grapefruit and citrus both are nouns.

Word	Noun	Adjective	Verb	Adverb
grapefruit	Yes	No	No	No
citrus	Yes	No	No	No

As nouns, citrus is a hypernym of grapefruit; that is, citrus is a word with a broader meaning than grapefruit:

grapefruit: large yellow fruit with somewhat acid juicy pulp; usual serving consists of a half
citrus: any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions

Other hypernyms of grapefruit include citrous fruit, citrus fruit.

As nouns, citrus is a hypernym of grapefruit; that is, citrus is a word with a broader meaning than grapefruit:

grapefruit: citrus tree bearing large round edible fruit having a thick yellow rind and juicy somewhat acid pulp
citrus: any of numerous tropical usually thorny evergreen trees of the genus Citrus having leathery evergreen leaves and widely cultivated for their juicy edible fruits having leathery aromatic rinds

Other hypernyms of grapefruit include citrus tree.

grapefruit (noun)	citrus (noun)
large yellow fruit with somewhat acid juicy pulp; usual serving consists of a half	any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions
citrus tree bearing large round edible fruit having a thick yellow rind and juicy somewhat acid pulp	any of numerous tropical usually thorny evergreen trees of the genus Citrus having leathery evergreen leaves and widely cultivated for their juicy edible fruits having leathery aromatic rinds