thick-skulled vs boneheaded

thick-skulled and boneheaded both are adjectives.

Word	Noun	Adjective	Verb	Adverb
thick-skulled	No	Yes	No	No
boneheaded	No	Yes	No	No

As adjectives, thick-skulled and boneheaded are synonyms defined as:

Other synonyms of thick-skulled include blockheaded, duncical, duncish, fatheaded, loggerheaded, thick, thickheaded, wooden-headed.

thick-skulled (adjective)	boneheaded (adjective)
(used informally) stupid	(used informally) stupid