inroad vs encroachment

inroad and encroachment both are nouns.

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

As nouns, encroachment is a hypernym of inroad; that is, encroachment is a word with a broader meaning than inroad:

Other hypernyms of inroad include intrusion, trespass, usurpation, violation.

inroad (noun)	encroachment (noun)
an invasion or hostile attack	entry to another's property without right or permission
an encroachment or intrusion	influencing strongly
	any entry into an area not previously occupied