decompression vs decipherment

decompression and decipherment both are nouns.

Word	Noun	Adjective	Verb	Adverb
decompression	Yes	No	No	No
decipherment	Yes	No	No	No

As nouns, decipherment is a hypernym of decompression; that is, decipherment is a word with a broader meaning than decompression:

decompression: restoring compressed information to its normal form for use or display
decipherment: the activity of making clear or converting from code into plain text

Other hypernyms of decompression include decoding, decryption.

decompression (noun)	decipherment (noun)
relieving pressure (especially bringing a compressed person gradually back to atmospheric pressure)	the activity of making clear or converting from code into plain text
restoring compressed information to its normal form for use or display