pig-headedly vs mulishly

pig-headedly and mulishly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
pig-headedly	No	No	No	Yes
mulishly	No	No	No	Yes

As adverbs, pig-headedly and mulishly are synonyms defined as:

Other synonyms of pig-headedly include cussedly, obdurately, obstinately, stubbornly.

pig-headedly (adverb)	mulishly (adverb)
in a stubborn unregenerate manner	in a stubborn unregenerate manner