distress call vs distress signal

distress call and distress signal both are nouns.

Word	Noun	Adjective	Verb	Adverb
distress call	Yes	No	No	No
distress signal	Yes	No	No	No

As nouns, distress call and distress signal are synonyms defined as:

distress call and distress signal: an internationally recognized signal sent out by a ship or plane indicating that help is needed

distress call (noun)	distress signal (noun)
an internationally recognized signal sent out by a ship or plane indicating that help is needed	an internationally recognized signal sent out by a ship or plane indicating that help is needed