opener vs bottle opener

opener and bottle opener both are nouns.

Word	Noun	Adjective	Verb	Adverb
opener	Yes	No	No	No
bottle opener	Yes	No	No	No

As nouns, bottle opener is a hyponym of opener; that is, bottle opener is a word with a more specific, narrower meaning than opener:

Other hyponyms of opener include can opener, tin opener, latchstring.

opener (noun)	bottle opener (noun)
a hand tool used for opening sealed containers (bottles or cans)	an opener for removing caps or corks from bottles
the first event in a series
a person who unfastens or unwraps or opens