tacheometer vs tachymeter

tacheometer and tachymeter both are nouns.

Word	Noun	Adjective	Verb	Adverb
tacheometer	Yes	No	No	No
tachymeter	Yes	No	No	No

As nouns, tacheometer and tachymeter are synonyms defined as:

tacheometer and tachymeter: a theodolite designed for rapid measurements

tacheometer (noun)	tachymeter (noun)
a theodolite designed for rapid measurements	a theodolite designed for rapid measurements