stone-deaf vs deaf as a post

stone-deaf and deaf as a post both are adjectives.

Word	Noun	Adjective	Verb	Adverb
stone-deaf	No	Yes	No	No
deaf as a post	No	Yes	No	No

As adjectives, stone-deaf and deaf as a post are synonyms defined as:

Other synonyms of stone-deaf include profoundly deaf, unhearing.

stone-deaf (adjective)	deaf as a post (adjective)
totally deaf; unable to hear anything	totally deaf; unable to hear anything