Honey contains several organic acids naturally in varying amounts including, but not limited to, oxalic, malic, formic, ascorbic, citric and acetic. These make the pH of honey more acidic than syrup. So does the vinegar.
Essential oils, while not naturally in concentrated amounts are in honey in small amounts. Still I would rather not use them as they are antimicrobial and the hive is dependent on may microbes for it's very existence.