decline in quality vs worsening

decline in quality and worsening both are nouns.

Word	Noun	Adjective	Verb	Adverb
decline in quality	Yes	No	No	No
worsening	Yes	Yes	No	No

As nouns, decline in quality and worsening are synonyms defined as:

decline in quality and worsening: process of changing to an inferior state

Other synonyms of decline in quality include declension, deterioration.

decline in quality (noun)	worsening (noun)
process of changing to an inferior state	changing something with the result that it becomes worse
	process of changing to an inferior state

decline in quality (adjective)	worsening (adjective)
	changing for the worse