e-Sword study notes do not sync across devices, as far as I know. So, even if your iPad and your Mac are signed into the same Apple ID, your notes will not be the same across both devices.
e-Sword X on the Mac and e-Sword HD on the iPad are separate purchases from the App Store (they are, in fact, separate applications). It would definitely be possible to have your iPad signed into one Apple ID and your Mac signed into another Apple ID. But you would have to purchase e-Sword X on your Mac (which you have probably already done) and purchase e-Sword HD (the iPad version) on your iPad.
Anyway, I hope this might be helpful to you.