inferno vs hell on earth

inferno and hell on earth both are nouns.

Word	Noun	Adjective	Verb	Adverb
inferno	Yes	No	No	No
hell on earth	Yes	No	No	No

As nouns, inferno and hell on earth are synonyms defined as:

Other synonyms of inferno include hell, hellhole, snake pit, the pits.

inferno (noun)	hell on earth (noun)
a very intense and uncontrolled fire	any place of pain and turmoil
any place of pain and turmoil