addle-head vs birdbrain

addle-head and birdbrain both are nouns.

Word	Noun	Adjective	Verb	Adverb
addle-head	Yes	No	No	No
birdbrain	Yes	No	No	No

As nouns, addle-head and birdbrain are synonyms defined as:

addle-head and birdbrain: a person with confused ideas; incapable of serious thought

Other synonyms of addle-head include addlehead, loon.

addle-head (noun)	birdbrain (noun)
a person with confused ideas; incapable of serious thought	a person with confused ideas; incapable of serious thought