pudding head vs stupid person

pudding head and stupid person both are nouns.

Word	Noun	Adjective	Verb	Adverb
pudding head	Yes	No	No	No
stupid person	Yes	No	No	No

As nouns, pudding head and stupid person are synonyms defined as:

Other synonyms of pudding head include dolt, dullard, pillock, poor fish, pudden-head, stupe, stupid.

pudding head (noun)	stupid person (noun)
a person who is not very bright	a person who is not very bright