chopper vs butcher knife

chopper and butcher knife both are nouns.

Word	Noun	Adjective	Verb	Adverb
chopper	Yes	No	No	No
butcher knife	Yes	No	No	No

As nouns, butcher knife is a hypernym of chopper; that is, butcher knife is a word with a broader meaning than chopper:

chopper (noun)	butcher knife (noun)
a grounder that bounces high in the air	a large sharp knife for cutting or trimming meat
a butcher's knife having a large square blade
an aircraft without wings that obtains its lift from the rotation of overhead blades
informal terms for a human `tooth'