fruitcake vs eccentric person

fruitcake and eccentric person both are nouns.

Word	Noun	Adjective	Verb	Adverb
fruitcake	Yes	No	No	No
eccentric person	Yes	No	No	No

As nouns, eccentric person is a hypernym of fruitcake; that is, eccentric person is a word with a broader meaning than fruitcake:

Other hypernyms of fruitcake include eccentric, flake, geek, oddball.

fruitcake (noun)	eccentric person (noun)
a rich cake containing dried fruit and nuts and citrus peel and so on	a person with an unusual or odd personality
a whimsically eccentric person