lightheaded vs empty-headed

lightheaded and empty-headed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
lightheaded	No	Yes	No	No
empty-headed	No	Yes	No	No

As adjectives, lightheaded and empty-headed are synonyms defined as:

Other synonyms of lightheaded include airheaded, dizzy, featherbrained, giddy, light-headed, silly.

lightheaded (adjective)	empty-headed (adjective)
lacking seriousness; given to frivolity	lacking seriousness; given to frivolity
weak and likely to lose consciousness