choking vs smothering

choking is a noun but smothering is not a noun.

Word	Noun	Adjective	Verb	Adverb
choking	Yes	Yes	No	No
smothering	No	Yes	No	No

As adjectives, choking and smothering are synonyms defined as:

choking and smothering: causing difficulty in breathing especially through lack of fresh air and presence of heat

Other synonyms of choking include suffocating, suffocative.

choking (noun)	smothering (noun)
the act of suffocating (someone) by constricting the windpipe
a condition caused by blocking the airways to the lungs (as with food or swelling of the larynx)

choking (adjective)	smothering (adjective)
causing difficulty in breathing especially through lack of fresh air and presence of heat	causing difficulty in breathing especially through lack of fresh air and presence of heat