WATS line vs telephone circuit

WATS line and telephone circuit both are nouns.

Word	Noun	Adjective	Verb	Adverb
WATS line	Yes	No	No	No
telephone circuit	Yes	No	No	No

As nouns, telephone circuit is a hypernym of WATS line; that is, telephone circuit is a word with a broader meaning than WATS line:

WATS line: a telephone line; long distance service at fixed rates for fixed zones; an acronym for wide area telephone service
telephone circuit: a telephone connection

Other hypernyms of WATS line include line, phone line, subscriber line, telephone line.

WATS line (noun)	telephone circuit (noun)
a telephone line; long distance service at fixed rates for fixed zones; an acronym for wide area telephone service	a telephone connection