thermos flask vs thermos

thermos flask and thermos both are nouns.

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

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

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

Other synonyms of thermos flask include thermos bottle.

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