underground press vs samizdat

underground press and samizdat both are nouns.

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

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

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

underground press (noun)	samizdat (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