abatement vs subsidence

abatement and subsidence both are nouns.

Word	Noun	Adjective	Verb	Adverb
abatement	Yes	No	No	No
subsidence	Yes	No	No	No

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

abatement: an interruption in the intensity or amount of something
subsidence: an abatement in intensity or degree (as in the manifestations of a disease)

Other hyponyms of abatement include defervescence, remission, remittal.

abatement (noun)	subsidence (noun)
the act of abating	a gradual sinking to a lower level
an interruption in the intensity or amount of something	the sudden collapse of something into a hollow beneath it
	an abatement in intensity or degree (as in the manifestations of a disease)