overpressure vs air pressure

overpressure and air pressure both are nouns.

Word	Noun	Adjective	Verb	Adverb
overpressure	Yes	No	No	No
air pressure	Yes	No	No	No

As nouns, air pressure is a hypernym of overpressure; that is, air pressure is a word with a broader meaning than overpressure:

overpressure: a transient air pressure greater than the surrounding atmospheric pressure
air pressure: the pressure exerted by the atmosphere

Other hypernyms of overpressure include atmospheric pressure, pressure.

overpressure (noun)	air pressure (noun)
a transient air pressure greater than the surrounding atmospheric pressure	the pressure exerted by the atmosphere