simulation vs mock-up

simulation and mock-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
simulation	Yes	No	No	No
mock-up	Yes	No	No	No

As nouns, mock-up is a hyponym of simulation; that is, mock-up is a word with a more specific, narrower meaning than simulation:

simulation: representation of something (sometimes on a smaller scale)
mock-up: full-scale working model of something built for study or testing or display

Other hyponyms of simulation include figure, globe, planetarium, restoration, roughcast.

simulation (noun)	mock-up (noun)
the act of giving a false appearance	full-scale working model of something built for study or testing or display
the act of imitating the behavior of some situation or some process by means of something suitably analogous (especially for the purpose of study or personnel training)
representation of something (sometimes on a smaller scale)
(computer science) the technique of representing the real world by a computer program