ugly duckling vs worker

ugly duckling and worker both are nouns.

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

As nouns, worker is a hypernym of ugly duckling; that is, worker 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
worker: a person who acts and gets things done

Other hypernyms of ugly duckling include actor, doer.

ugly duckling (noun)	worker (noun)
an ugly or unpromising child who grows into a beautiful or worthy person	sterile member of a colony of social insects that forages for food and cares for the larvae
	a person who works at a specific occupation
	a member of the working class (not necessarily employed)
	a person who acts and gets things done