firefly vs glowworm

firefly and glowworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
firefly	Yes	No	No	No
glowworm	Yes	No	No	No

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

firefly: nocturnal beetle common in warm regions having luminescent abdominal organs
glowworm: the luminous larva or wingless grub-like female of a firefly

firefly (noun)	glowworm (noun)
nocturnal beetle common in warm regions having luminescent abdominal organs	the luminous larva or wingless grub-like female of a firefly
tropical American click beetle having bright luminous spots