encroachment vs impingement

encroachment and impingement both are nouns.

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

As nouns, encroachment and impingement are synonyms defined as:

Other synonyms of encroachment include impact.

encroachment (noun)	impingement (noun)
entry to another's property without right or permission	influencing strongly
influencing strongly	a sharp collision produced by striking or dashing against something
any entry into an area not previously occupied