toroid vs annulus

toroid and annulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
toroid	Yes	No	No	No
annulus	Yes	No	No	No

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

Other hyponyms of toroid include anchor ring, doughnut, halo, ring.

toroid (noun)	annulus (noun)
a ring-shaped surface generated by rotating a circle around an axis that does not intersect the circle	(Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
the doughnut-shaped object enclosed by a torus	a toroidal shape