auto-alarm vs receiving system

auto-alarm and receiving system both are nouns.

Word	Noun	Adjective	Verb	Adverb
auto-alarm	Yes	No	No	No
receiving system	Yes	No	No	No

As nouns, receiving system is a hypernym of auto-alarm; that is, receiving system is a word with a broader meaning than auto-alarm:

auto-alarm: a radio receiving device used on ships that rings an alarm bell when a distress signal is received.
receiving system: set that receives radio or tv signals

Other hypernyms of auto-alarm include receiver.

auto-alarm (noun)	receiving system (noun)
a radio receiving device used on ships that rings an alarm bell when a distress signal is received.	set that receives radio or tv signals