Hi Miss G, a polished or skimmed record has if any small marks in the plastic rounded off and will have lost the sharp edge to the mark or scuff, glaze or shine will be affected as well.
I had a G- Panic Is On demo, for personal use! I used some Brasso (hence my term Polish) and removed 80% of the marks but the disc was frooked, sold it on then a week later its in the sales box as M-? more elbow grease and Tcut.
I think the term skimmed makes it sound professional like there is some special equipment used by a boffin in a white coat and not a bottle of car cleaner with Granny's old silk bloomers to buff it up.
A funny record is Cub The Wanderers Somebody Else's Sweetheart, A side is clean but the B side looks polished on all the copy's I have seen.