head-in-the-clouds vs scatterbrained

head-in-the-clouds and scatterbrained both are adjectives.

Word	Noun	Adjective	Verb	Adverb
head-in-the-clouds	No	Yes	No	No
scatterbrained	No	Yes	No	No

As adjectives, head-in-the-clouds and scatterbrained are synonyms defined as:

Other synonyms of head-in-the-clouds include flighty, flyaway.

head-in-the-clouds (adjective)	scatterbrained (adjective)
guided by whim and fancy	lacking sense or discretion
	guided by whim and fancy