french fries vs Irish potato

french fries and Irish potato both are nouns.

Word	Noun	Adjective	Verb	Adverb
french fries	Yes	No	No	No
Irish potato	Yes	No	No	No

As nouns, Irish potato is a hypernym of french fries; that is, Irish potato is a word with a broader meaning than french fries:

french fries: strips of potato fried in deep fat
Irish potato: an edible tuber native to South America; a staple food of Ireland

Other hypernyms of french fries include murphy, potato, spud, tater, white potato.

french fries (noun)	Irish potato (noun)
strips of potato fried in deep fat	an edible tuber native to South America; a staple food of Ireland