self-willed vs headstrong

self-willed and headstrong both are adjectives.

Word	Noun	Adjective	Verb	Adverb
self-willed	No	Yes	No	No
headstrong	No	Yes	No	No

As adjectives, self-willed and headstrong are synonyms defined as:

self-willed and headstrong: habitually disposed to disobedience and opposition

Other synonyms of self-willed include froward, wilful, willful.

self-willed (adjective)	headstrong (adjective)
habitually disposed to disobedience and opposition	habitually disposed to disobedience and opposition