adjustment vs tune-up

adjustment and tune-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
adjustment	Yes	No	No	No
tune-up	Yes	No	No	No

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

adjustment (noun)	tune-up (noun)
the act of making something different (as e.g. the size of a garment)	adjustments made to an engine to improve its performance
the act of adjusting something to match a standard	exercising in preparation for strenuous activity
making or becoming suitable; adjusting to circumstances
an amount added or deducted on the basis of qualifying circumstances
the process of adapting to something (such as environmental conditions)