Well depends on what you mean by "restore" there is "restore from back up" and "restore iPod".
When you "restore from back up" you are essentially recovering your device to a saved state, all the apps, contacts, data, settings, photos, etc that were included in the backup will be restored to the device.
When you "restore iPod" you are restoring it to factory defaults. This includes completely erasing everything on it. For your reference you may redownload apps you purchased for free.
selessSABOTAGE, you are little incorrect. The iTunes backup does not included synced media like app and music. If you restore from backup via iTunes if the synced media is not in the iTunes library it will not be on the iPod after restoring from backup.
You can redownload iTunes purchases by:
If you restore from iCloud backup all your iTunes purchases are restored to the iPod including iTunes purchased app and music.
lllaass, I appreciate your diligence in ensuring the original poster receives the most correct information. I completely understand that media and apps themselves are not included in back ups. If my post lead one to believe that was the case then perhaps I will find a more clear way to word future posts.
Once you restore from a back up the first thing that happens, or should happen, is the device syncs and re-adds all the items from the library.
Again, thank you for the clarification lllaass.