proclivity vs tendency

proclivity and tendency both are nouns.

Word	Noun	Adjective	Verb	Adverb
proclivity	Yes	No	No	No
tendency	Yes	No	No	No

As nouns, tendency is a hypernym of proclivity; that is, tendency is a word with a broader meaning than proclivity:

proclivity: a natural inclination
tendency: an attitude of mind especially one that favors one alternative over others

Other hypernyms of proclivity include disposition, inclination.

proclivity (noun)	tendency (noun)
a natural inclination	a characteristic likelihood of or natural disposition toward a certain condition or character or effect
	an attitude of mind especially one that favors one alternative over others
	an inclination to do something
	a general direction in which something tends to move