samizdat vs underground press

samizdat and underground press both are nouns.

Word	Noun	Adjective	Verb	Adverb
samizdat	Yes	No	No	No
underground press	Yes	No	No	No

As nouns, samizdat and underground press are synonyms defined as:

samizdat and underground press: a system of clandestine printing and distribution of dissident or banned literature

samizdat (noun)	underground press (noun)
a system of clandestine printing and distribution of dissident or banned literature	a system of clandestine printing and distribution of dissident or banned literature