troubling vs worrying

troubling is not a noun while worrying is a noun.

Word	Noun	Adjective	Verb	Adverb
troubling	No	Yes	No	No
worrying	Yes	Yes	No	No

As adjectives, troubling and worrying are synonyms defined as:

Other synonyms of troubling include distressful, distressing, disturbing, perturbing, worrisome.

troubling (noun)	worrying (noun)
	the act of harassing someone
	the act of moving something by repeated tugs or pushes

troubling (adjective)	worrying (adjective)
causing distress or worry or anxiety	causing distress or worry or anxiety