obstacle race vs foot race

obstacle race and foot race both are nouns.

Word	Noun	Adjective	Verb	Adverb
obstacle race	Yes	No	No	No
foot race	Yes	No	No	No

As nouns, foot race is a hypernym of obstacle race; that is, foot race is a word with a broader meaning than obstacle race:

Other hypernyms of obstacle race include footrace, run.

obstacle race (noun)	foot race (noun)
a race in which competitors must negotiate obstacles	a race run on foot