pussycat vs kitty-cat

pussycat and kitty-cat both are nouns.

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

As nouns, pussycat and kitty-cat are synonyms defined as:

Other synonyms of pussycat include kitty, puss, pussy.

pussycat (noun)	kitty-cat (noun)
informal terms referring to a domestic cat	informal terms referring to a domestic cat
a person who is regarded as easygoing and agreeable