Kendall's tau vs tau coefficient of correlation

Kendall's tau and tau coefficient of correlation both are nouns.

Word	Noun	Adjective	Verb	Adverb
Kendall's tau	Yes	No	No	No
tau coefficient of correlation	Yes	No	No	No

As nouns, Kendall's tau and tau coefficient of correlation are synonyms defined as:

Kendall's tau and tau coefficient of correlation: a nonparametric measure of the agreement between two rankings

Other synonyms of Kendall's tau include Kendall rank correlation.

Kendall's tau (noun)	tau coefficient of correlation (noun)
a nonparametric measure of the agreement between two rankings	a nonparametric measure of the agreement between two rankings