ratter vs terrier

ratter and terrier both are nouns.

Word	Noun	Adjective	Verb	Adverb
ratter	Yes	No	No	No
terrier	Yes	No	No	No

As nouns, terrier is a hypernym of ratter; that is, terrier is a word with a broader meaning than ratter:

ratter: any of several breeds of terrier developed to catch rats
terrier: any of several usually small short-bodied breeds originally trained to hunt animals living underground

ratter (noun)	terrier (noun)
any of several breeds of terrier developed to catch rats	any of several usually small short-bodied breeds originally trained to hunt animals living underground
a disloyal person who betrays or deserts his cause or religion or political party or friend etc.