panic attack vs fearfulness

panic attack and fearfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
panic attack	Yes	No	No	No
fearfulness	Yes	No	No	No

As nouns, fearfulness is a hypernym of panic attack; that is, fearfulness is a word with a broader meaning than panic attack:

panic attack: a sudden attack of fear
fearfulness: an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)

Other hypernyms of panic attack include fear, fright.

panic attack (noun)	fearfulness (noun)
a sudden attack of fear	the trait of being afraid
	an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)