foe vs contender

foe and contender both are nouns.

Word	Noun	Adjective	Verb	Adverb
foe	Yes	No	No	No
contender	Yes	No	No	No

As nouns, contender is a hypernym of foe; that is, contender is a word with a broader meaning than foe:

Other hypernyms of foe include challenger, competition, competitor, rival.

foe (noun)	contender (noun)
a personal enemy	the contestant you hope to defeat
an armed adversary (especially a member of an opposing military force)