the album artwork on my ipod is messed up

I just got a new ipod gen6 3 months ago or so. i scrimped and saved up for 5 months so you can understand my frustration. i added my music from my itunes and nearly every song has the wrong artwork. even the music that i bought right off the itunes store has the wrong artwork. however on my iphone when i look for the music i bought right from the store its got the right artwork there. like no matter where the songs come from they'll all trade artwork with each other. they usually keep the artwork they trade and not constantly trading. ive backed up and restored my ipod and then tried adding the music again and still didnt fix it. when i was using an ipod nano before i bought my new one, it did the same thing. the artwork is correct in itunes and when i plug in my ipod and open itunes and open the 'get info' on any song the artwork is correct. its only when im looking at a song from my ipod. just 15 minutes ago i tried to manually change the artwork on a couple songs. i googled the artwork, deleted what was already there in tunes and replaced it with what i googled. it looked good on itunes but watching it change on my ipod, my aaron carter artwork became sum 41 and sum 41 became the goofy movie soundtrack.