rock-ribbed vs die-hard

rock-ribbed and die-hard both are adjectives.

Word	Noun	Adjective	Verb	Adverb
rock-ribbed	No	Yes	No	No
die-hard	No	Yes	No	No

As adjectives, rock-ribbed and die-hard are synonyms defined as:

rock-ribbed (adjective)	die-hard (adjective)
tradition-bound and obstinately opinionated	tradition-bound and obstinately opinionated
abounding in or bordered by rocky cliffs or scarps