cryptograph vs secret writing

cryptograph and secret writing both are nouns.

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

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

Other synonyms of cryptograph include cryptogram.

cryptograph (noun)	secret writing (noun)
a device for deciphering codes and ciphers	act of writing in code or cipher
a piece of writing in code or cipher	a piece of writing in code or cipher
a secret method of writing