Answer:
they all mean the same thing, they explain or describe a noun.
Step-by-step explanation:
simple- means plain.
plain means simple.
definition of both:
plain= not decorated or elaborate; simple or ordinary in character.
simple= easily understood or done; presenting no difficulty.
they both meaning things that just aren't difficult to understand.
and common means=occurring, found, or done often; prevalent
basically occurringly found.
all words all have the same meaning generally, but techicnally they dont.
hope this helps :)