completion vs conclusion

completion and conclusion both are nouns.

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

As nouns, conclusion is a hypernym of completion; that is, conclusion is a word with a broader meaning than completion:

Other hypernyms of completion include ending, termination.

completion (noun)	conclusion (noun)
a concluding action	the act of ending something
(American football) a successful forward pass in football	the act of making up your mind about something
	a position or opinion or judgment reached after consideration
	an intuitive assumption
	the last section of a communication
	the proposition arrived at by logical reasoning (such as the proposition that must follow from the major and minor premises of a syllogism)
	a final settlement
	event whose occurrence ends something
	the temporal end; the concluding time