blackness vs pitch blackness

blackness and pitch blackness both are nouns.

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

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

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

blackness (noun)	pitch blackness (noun)
the quality or state of the achromatic color of least lightness (bearing the least resemblance to white)	total absence of light
total absence of light