thermos bottle vs thermos flask

thermos bottle and thermos flask both are nouns.

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

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

thermos bottle and thermos flask: vacuum flask that preserves temperature of hot or cold drinks

Other synonyms of thermos bottle include thermos.

thermos bottle (noun)	thermos flask (noun)
vacuum flask that preserves temperature of hot or cold drinks	vacuum flask that preserves temperature of hot or cold drinks