the difference is,
vid mod locks the card to 1.4v. some cards red screen at that volts booting in to windows. So if you have an unlucky card you will have some problems. Vid mod also limits you to 1.62v in Ab. which is too little. You can still own with vid mod tho no problems.
Vcore mod is like a normal mod, goes from 1v to 1.35v. then do the rest with AB
DON'T use vcore mod with the NORMAL ln2 bios, that ln2 bios has some weird volting going on so you might see random .2 jumps in vcore. The MOA ln2 bios is perfect tho