penetration vs invasion

penetration and invasion both are nouns.

Word	Noun	Adjective	Verb	Adverb
penetration	Yes	No	No	No
invasion	Yes	No	No	No

As nouns, invasion is a hyponym of penetration; that is, invasion is a word with a more specific, narrower meaning than penetration:

penetration: an attack that penetrates into enemy territory
invasion: the act of invading; the act of an army that invades for conquest or plunder

Other hyponyms of penetration include interpenetration, breakthrough, infiltration, foray, maraud, raid.

penetration (noun)	invasion (noun)
an attack that penetrates into enemy territory	the act of invading; the act of an army that invades for conquest or plunder
the act of entering into or through something	any entry into an area not previously occupied
the act (by a man) of inserting his penis into the vagina of a woman	(pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body
the depth to which something penetrates (especially the depth reached by a projectile that hits a target)
the ability to make way into or through something
clear or deep perception of a situation