enclosure vs encasement

enclosure and encasement both are nouns.

Word	Noun	Adjective	Verb	Adverb
enclosure	Yes	No	No	No
encasement	Yes	No	No	No

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

Other hyponyms of enclosure include boxing, packing, incasement.

enclosure (noun)	encasement (noun)
the act of enclosing something inside something else	the act of enclosing something in a case
a structure consisting of an area that has been enclosed for some purpose
something (usually a supporting document) that is enclosed in an envelope with a covering letter
a naturally enclosed space