blowhole vs venthole

blowhole and venthole both are nouns.

Word	Noun	Adjective	Verb	Adverb
blowhole	Yes	No	No	No
venthole	Yes	No	No	No

As nouns, blowhole and venthole are synonyms defined as:

Other synonyms of blowhole include vent-hole, vent.

blowhole (noun)	venthole (noun)
a hole for the escape of gas or air	a hole for the escape of gas or air
the spiracle of a cetacean located far back on the skull