decryption vs cryptography

decryption and cryptography both are nouns.

Word	Noun	Adjective	Verb	Adverb
decryption	Yes	No	No	No
cryptography	Yes	No	No	No

As nouns, cryptography is a hypernym of decryption; that is, cryptography is a word with a broader meaning than decryption:

decryption: the activity of making clear or converting from code into plain text
cryptography: act of writing in code or cipher

Other hypernyms of decryption include coding, secret writing, steganography.

decryption (noun)	cryptography (noun)
the activity of making clear or converting from code into plain text	act of writing in code or cipher
	the science of analyzing and deciphering codes and ciphers and cryptograms