city boy vs slicker

city boy and slicker both are nouns.

Word	Noun	Adjective	Verb	Adverb
city boy	Yes	No	No	No
slicker	Yes	No	No	No

As nouns, slicker is a hypernym of city boy; that is, slicker is a word with a broader meaning than city boy:

city boy (noun)	slicker (noun)
a city dweller with sophisticated manners and clothing	a macintosh made from cotton fabric treated with oil and pigment to make it waterproof
	someone who leads you to believe something that is not true
	a person with good manners and stylish clothing