burglar alarm vs warning signal

burglar alarm and warning signal both are nouns.

Word	Noun	Adjective	Verb	Adverb
burglar alarm	Yes	No	No	No
warning signal	Yes	No	No	No

As nouns, warning signal is a hypernym of burglar alarm; that is, warning signal is a word with a broader meaning than burglar alarm:

Other hypernyms of burglar alarm include alarm, alarum, alert.

burglar alarm (noun)	warning signal (noun)
a warning device that is tripped off by the occurrence of a burglary	an automatic signal (usually a sound) warning of danger
a loud warning signal produced by a burglar alarm