closing vs completion

closing and completion both are nouns.

Word	Noun	Adjective	Verb	Adverb
closing	Yes	Yes	No	No
completion	Yes	No	No	No

As nouns, closing and completion are synonyms defined as:

Other synonyms of closing include culmination, mop up, windup.

closing (noun)	completion (noun)
termination of operations	a concluding action
the act of closing something	(American football) a successful forward pass in football
a concluding action
approaching a particular destination; a coming closer; a narrowing of a gap
the last section of a communication

closing (adjective)	completion (adjective)
final or ending