ski vs schuss

ski is a noun but schuss is not a noun.

Word	Noun	Adjective	Verb	Adverb
ski	Yes	No	Yes	No
schuss	No	No	Yes	No

As verbs, schuss is a hyponym of ski; that is, schuss is a word with a more specific, narrower meaning than ski:

Other hyponyms of ski include wedel, hot-dog, slalom, water ski.

ski (noun)	schuss (noun)
narrow wood or metal or plastic runners used in pairs for gliding over snow

ski (verb)	schuss (verb)
move along on skis	ski downhill