windstorm vs whirlwind

windstorm and whirlwind both are nouns.

Word	Noun	Adjective	Verb	Adverb
windstorm	Yes	No	No	No
whirlwind	Yes	No	No	No

As nouns, whirlwind is a hyponym of windstorm; that is, whirlwind is a word with a more specific, narrower meaning than windstorm:

windstorm: a storm consisting of violent winds
whirlwind: a more or less vertical column of air whirling around itself as it moves over the surface of the Earth

Other hyponyms of windstorm include cyclone, dust storm, duster, sandstorm, sirocco, tempest.

windstorm (noun)	whirlwind (noun)
a storm consisting of violent winds	a more or less vertical column of air whirling around itself as it moves over the surface of the Earth