ugly duckling vs doer

ugly duckling and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
ugly duckling	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of ugly duckling; that is, doer is a word with a broader meaning than ugly duckling:

ugly duckling: an ugly or unpromising child who grows into a beautiful or worthy person
doer: a person who acts and gets things done

Other hypernyms of ugly duckling include actor, worker.

ugly duckling (noun)	doer (noun)
an ugly or unpromising child who grows into a beautiful or worthy person	a person who acts and gets things done