total darkness vs pitch blackness

total darkness and pitch blackness both are nouns.

Word	Noun	Adjective	Verb	Adverb
total darkness	Yes	No	No	No
pitch blackness	Yes	No	No	No

As nouns, total darkness and pitch blackness are synonyms defined as:

Other synonyms of total darkness include black, blackness, lightlessness.

total darkness (noun)	pitch blackness (noun)
total absence of light	total absence of light