Yes, it is exactly as @spdl79 says.
The verb in Greek " ζωγραφίζω" means to draw or to paint only the artistic kind of painting. And the person who does it is a "ζωγράφος".
The general word for "artist" is "καλλιτέκνης".
For your walls etc you would use "βάφω' and the person who does is a "βαφέας" or "μπογιατζής".
I personally wouldn't say so - as far as I understand things they're different words with different meanings in both English and Greek. Artist in Greek is καλλιτέχνης.
Unless you're talking about tradespeople, all painters are artists, but not all artists are painters - an artist could be a sculptor or a musician or a dancer. In other words painters/ζωγράφοι are a subset of artists/καλλιτέχνες.
A mod or a native speaker might have a different opinion though.