kiddy vs tiddler

kiddy and tiddler both are nouns.

Word	Noun	Adjective	Verb	Adverb
kiddy	Yes	No	No	No
tiddler	Yes	No	No	No

As nouns, tiddler is a hypernym of kiddy; that is, tiddler is a word with a broader meaning than kiddy:

Other hypernyms of kiddy include child, fry, kid, minor, nestling, nipper, shaver, small fry, tike, tyke, youngster.

kiddy (noun)	tiddler (noun)
informal term for a young child	a young person of either sex