panel heating vs heating system

panel heating and heating system both are nouns.

Word	Noun	Adjective	Verb	Adverb
panel heating	Yes	No	No	No
heating system	Yes	No	No	No

As nouns, heating system is a hypernym of panel heating; that is, heating system is a word with a broader meaning than panel heating:

panel heating: heating system consisting of wall or floor or baseboard or ceiling panels containing electric conductors or heating pipes
heating system: utility to warm a building

Other hypernyms of panel heating include heat, heating, heating plant.

panel heating (noun)	heating system (noun)
heating system consisting of wall or floor or baseboard or ceiling panels containing electric conductors or heating pipes	utility to warm a building