tachygraphy vs stenography

tachygraphy and stenography both are nouns.

Word	Noun	Adjective	Verb	Adverb
tachygraphy	Yes	No	No	No
stenography	Yes	No	No	No

As nouns, tachygraphy and stenography are synonyms defined as:

tachygraphy and stenography: a method of writing rapidly using an abbreviated symbolic system

Other synonyms of tachygraphy include shorthand.

tachygraphy (noun)	stenography (noun)
a method of writing rapidly using an abbreviated symbolic system	the act or art of writing in shorthand
	a method of writing rapidly using an abbreviated symbolic system