Different song counts between iOS Music & iTunes for Windows

I have my iTunes library set to sync only selected songs/playlists/etc. to my phone; but when iTunes showed the selected-songs count as 2158, my phone's settings after syncing showed 2160 songs. Now that the iTunes count is up to 2171, the phone count is up to 2175. I have no idea where the extra 4 songs are coming from--how can I find & get rid of them?