hardened vs treated

hardened and treated both are adjectives.

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

As adjectives, hardened and treated are synonyms defined as:

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

Other synonyms of hardened include tempered, toughened.

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