case-hardened vs hard-boiled

case-hardened and hard-boiled both are adjectives.

Word	Noun	Adjective	Verb	Adverb
case-hardened	No	Yes	No	No
hard-boiled	No	Yes	No	No

As adjectives, case-hardened and hard-boiled are synonyms defined as:

Other synonyms of case-hardened include hardened.

case-hardened (adjective)	hard-boiled (adjective)
used of persons; emotionally hardened	(eggs) cooked until the yolk is solid
	used of persons; emotionally hardened
	tough and callous by virtue of experience