motion sickness vs nausea

motion sickness and nausea both are nouns.

Word	Noun	Adjective	Verb	Adverb
motion sickness	Yes	No	No	No
nausea	Yes	No	No	No

As nouns, nausea is a hypernym of motion sickness; that is, nausea is a word with a broader meaning than motion sickness:

motion sickness: the state of being dizzy or nauseated because of the motions that occur while traveling in or on a moving vehicle
nausea: the state that precedes vomiting

Other hypernyms of motion sickness include ailment, complaint, ill, sickness.

motion sickness (noun)	nausea (noun)
the state of being dizzy or nauseated because of the motions that occur while traveling in or on a moving vehicle	disgust so strong it makes you feel sick
	the state that precedes vomiting