stupid person vs pudden-head

stupid person and pudden-head both are nouns.

Word	Noun	Adjective	Verb	Adverb
stupid person	Yes	No	No	No
pudden-head	Yes	No	No	No

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

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

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