ringing vs bell ringing

ringing and bell ringing both are nouns.

Word	Noun	Adjective	Verb	Adverb
ringing	Yes	No	No	No
bell ringing	Yes	No	No	No

As nouns, bell ringing is a hyponym of ringing; that is, bell ringing is a word with a more specific, narrower meaning than ringing:

ringing (noun)	bell ringing (noun)
having the character of a loud deep sound; the quality of being resonant	playing a set of bells that are (usually) hung in a tower
the giving of a ring as a token of engagement	persuasion of voters in a political campaign
the sound of a bell ringing	the sound of someone playing a set of bells