teacher's pet vs ducky

teacher's pet and ducky both are nouns.

Word	Noun	Adjective	Verb	Adverb
teacher's pet	Yes	No	No	No
ducky	Yes	No	No	No

As nouns, ducky is a hypernym of teacher's pet; that is, ducky is a word with a broader meaning than teacher's pet:

Other hypernyms of teacher's pet include darling, dearie, deary, favorite, favourite, pet.

teacher's pet (noun)	ducky (noun)
the teacher's favorite student	a special loved one