tiger moth vs arctiid

tiger moth and arctiid both are nouns.

Word	Noun	Adjective	Verb	Adverb
tiger moth	Yes	No	No	No
arctiid	Yes	No	No	No

As nouns, arctiid is a hypernym of tiger moth; that is, arctiid is a word with a broader meaning than tiger moth:

tiger moth: medium-sized moth with long richly colored and intricately patterned wings; larvae are called woolly bears
arctiid: stout-bodied broad-winged moth with conspicuously striped or spotted wings; larvae are hairy caterpillars

Other hypernyms of tiger moth include arctiid moth.

tiger moth (noun)	arctiid (noun)
medium-sized moth with long richly colored and intricately patterned wings; larvae are called woolly bears	stout-bodied broad-winged moth with conspicuously striped or spotted wings; larvae are hairy caterpillars