plastering machine vs plaster machine

plastering machine and plaster machine both are nouns.

Word	Noun	Adjective	Verb	Adverb
plastering machine	Yes	No	No	No
plaster machine	Yes	No	No	No

As nouns, plastering machine and plaster machine are synonyms defined as:

Other synonyms of plastering machine include rendering machine.

plastering machine (noun)	plaster machine (noun)
a machine for wall rendering.	a machine for wall rendering.