opener vs can opener

opener and can opener both are nouns.

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

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

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

opener (noun)	can opener (noun)
a hand tool used for opening sealed containers (bottles or cans)	a device for cutting cans open
the first event in a series
a person who unfastens or unwraps or opens