envelopment vs insertion

envelopment and insertion both are nouns.

Word	Noun	Adjective	Verb	Adverb
envelopment	Yes	No	No	No
insertion	Yes	No	No	No

As nouns, insertion is a hypernym of envelopment; that is, insertion is a word with a broader meaning than envelopment:

Other hypernyms of envelopment include introduction, intromission.

envelopment (noun)	insertion (noun)
the act of enclosing something inside something else	the act of putting one thing into another
	a message (spoken or written) that is introduced or inserted