treated vs hardened

treated and hardened both are adjectives.

Word	Noun	Adjective	Verb	Adverb
treated	No	Yes	No	No
hardened	No	Yes	No	No

As adjectives, treated and hardened are synonyms defined as:

treated and hardened: made hard or flexible or resilient especially by heat treatment

Other synonyms of treated include tempered, toughened.

treated (adjective)	hardened (adjective)
subjected to a physical (or chemical) treatment or action or agent	made hard or flexible or resilient especially by heat treatment
given medical care or treatment	protected against attack (especially by nuclear weapons)
made hard or flexible or resilient especially by heat treatment	made tough by habitual exposure
	converted to solid form (as concrete)
	used of persons; emotionally hardened