fun vs wordplay

fun and wordplay both are nouns.

Word	Noun	Adjective	Verb	Adverb
fun	Yes	No	No	No
wordplay	Yes	No	No	No

As nouns, wordplay is a hyponym of fun; that is, wordplay is a word with a more specific, narrower meaning than fun:

fun: verbal wit or mockery (often at another's expense but not to be taken seriously)
wordplay: a humorous play on words

fun (noun)	wordplay (noun)
activities that are enjoyable or amusing	a humorous play on words
violent and excited activity
a disposition to find (or make) causes for amusement
verbal wit or mockery (often at another's expense but not to be taken seriously)