As adjectives the difference between communal and communist
is that communal is pertaining to a community while communist is relating to a (nominally) communist party.
As a noun communist is
a member of a (nominally) communist party.
communist
English
Adjective
(head)
Of, relating to, supporting, or advocating communism.
Noun
(
en noun)
An advocate of a society based on the common ownership of property; a proponent of communism.
(nonstandard) Any revolutionary or subversive radical.