usurpation vs encroachment

usurpation and encroachment both are nouns.

Word	Noun	Adjective	Verb	Adverb
usurpation	Yes	No	No	No
encroachment	Yes	No	No	No

As nouns, usurpation and encroachment are synonyms defined as:

usurpation and encroachment: entry to another's property without right or permission

Other synonyms of usurpation include intrusion, trespass, violation.

usurpation (noun)	encroachment (noun)
wrongfully seizing and holding (an office or powers) by force (especially the seizure of a throne or supreme authority)	entry to another's property without right or permission
entry to another's property without right or permission	influencing strongly
	any entry into an area not previously occupied