pussycat vs kitty

pussycat and kitty both are nouns.

Word	Noun	Adjective	Verb	Adverb
pussycat	Yes	No	No	No
kitty	Yes	No	No	No

As nouns, pussycat and kitty are synonyms defined as:

Other synonyms of pussycat include kitty-cat, puss, pussy.

pussycat (noun)	kitty (noun)
informal terms referring to a domestic cat	informal terms referring to a domestic cat
a person who is regarded as easygoing and agreeable	young domestic cat
	the combined stakes of the betters
	the cumulative amount involved in a game (such as poker)