vacuum bottle vs vacuum flask

vacuum bottle and vacuum flask both are nouns.

Word	Noun	Adjective	Verb	Adverb
vacuum bottle	Yes	No	No	No
vacuum flask	Yes	No	No	No

As nouns, vacuum bottle and vacuum flask are synonyms defined as:

vacuum bottle and vacuum flask: flask with double walls separated by vacuum; used to maintain substances at high or low temperatures

vacuum bottle (noun)	vacuum flask (noun)
flask with double walls separated by vacuum; used to maintain substances at high or low temperatures	flask with double walls separated by vacuum; used to maintain substances at high or low temperatures