secret writing vs cryptography

secret writing and cryptography both are nouns.

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

As nouns, secret writing and cryptography are synonyms defined as:

Other synonyms of secret writing include coding, steganography.

secret writing (noun)	cryptography (noun)
act of writing in code or cipher	act of writing in code or cipher
a piece of writing in code or cipher	the science of analyzing and deciphering codes and ciphers and cryptograms