cryptography vs secret writing

cryptography and secret writing both are nouns.

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

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

Other synonyms of cryptography include coding, steganography.

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