writing vs cryptography

writing and cryptography both are nouns.

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

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

Other hyponyms of writing include coding, secret writing, steganography, handwriting, inscription, notation.

writing (noun)	cryptography (noun)
the activity of putting something in written form	act of writing in code or cipher
the act of creating written works	the science of analyzing and deciphering codes and ciphers and cryptograms
the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)
letters or symbols that are written or imprinted on a surface to represent the sounds or words of a language
(usually plural) the collected work of an author