hard-boiled vs case-hardened

hard-boiled and case-hardened both are adjectives.

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

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

Other synonyms of hard-boiled include hardened.

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