hair dryer vs blow drier

hair dryer and blow drier both are nouns.

Word	Noun	Adjective	Verb	Adverb
hair dryer	Yes	No	No	No
blow drier	Yes	No	No	No

As nouns, hair dryer and blow drier are synonyms defined as:

hair dryer and blow drier: a hand-held electric blower that can blow warm air onto the hair; used for styling hair

Other synonyms of hair dryer include blow dryer, hair drier, hand blower.

hair dryer (noun)	blow drier (noun)
a hand-held electric blower that can blow warm air onto the hair; used for styling hair	a hand-held electric blower that can blow warm air onto the hair; used for styling hair