fuel cell vs electric cell

fuel cell and electric cell both are nouns.

Word	Noun	Adjective	Verb	Adverb
fuel cell	Yes	No	No	No
electric cell	Yes	No	No	No

As nouns, electric cell is a hypernym of fuel cell; that is, electric cell is a word with a broader meaning than fuel cell:

fuel cell: cell that produces electricity by oxidation of fuel (hydrogen and oxygen or zinc and air); often used in electric cars
electric cell: a device that delivers an electric current as the result of a chemical reaction

Other hypernyms of fuel cell include cell.

fuel cell (noun)	electric cell (noun)
cell that produces electricity by oxidation of fuel (hydrogen and oxygen or zinc and air); often used in electric cars	a device that delivers an electric current as the result of a chemical reaction