rectification vs changeover

rectification and changeover both are nouns.

Word	Noun	Adjective	Verb	Adverb
rectification	Yes	No	No	No
changeover	Yes	No	No	No

As nouns, changeover is a hypernym of rectification; that is, changeover is a word with a broader meaning than rectification:

Other hypernyms of rectification include conversion, transition.

rectification (noun)	changeover (noun)
the act of offering an improvement to replace a mistake; setting right	an event that results in a transformation
determination of the length of a curve; finding a straight line equal in length to a given curve
the conversion of alternating current to direct current
(chemistry) the process of refinement or purification of a substance by distillation