disregarding vs regardless

disregarding is not an adjective while regardless is an adjective.

Word	Noun	Adjective	Verb	Adverb
disregarding	No	No	No	Yes
regardless	No	Yes	No	Yes

As adverbs, disregarding and regardless are synonyms defined as:

disregarding and regardless: in spite of everything; without regard to drawbacks

Other synonyms of disregarding include disregardless, irrespective, no matter.

disregarding (adjective)	regardless (adjective)
	(usually followed by `of') without due thought or consideration

disregarding (adverb)	regardless (adverb)
in spite of everything; without regard to drawbacks	in spite of everything; without regard to drawbacks