incursion vs invasion

incursion and invasion both are nouns.

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

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

incursion: 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 incursion include interpenetration, breakthrough, infiltration, foray, maraud, raid.

incursion (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 some territory or domain (often in large numbers)	any entry into an area not previously occupied
the mistake of incurring liability or blame	(pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body