retrofit vs install

retrofit is a noun but install is not a noun.

Word	Noun	Adjective	Verb	Adverb
retrofit	Yes	No	Yes	No
install	No	No	Yes	No

As verbs, install is a hypernym of retrofit; that is, install is a word with a broader meaning than retrofit:

Other hypernyms of retrofit include instal, put in, set up.

retrofit (noun)	install (noun)
the act of adding a component or accessory to something that did not have it when it was manufactured
a component or accessory added to something after it has been manufactured

retrofit (verb)	install (verb)
substitute new or modernized parts or equipment for older ones	set up for use
fit in or on an existing structure, such as an older house	place
provide with parts, devices, or equipment not available or in use at the time of the original manufacture	put into an office or a position