The lines by MGM in Vegas are different than the rest of the US. Similarly, the lines for William Hill are different than the lines used elsewhere as well. Most of the reason for that are innate technological hurdles that are created because of the restrictions in NV. For instance, MGM Nevada runs on Microsoft Access (yes, it's just a MS Access database from the 90's).
When legalization boomed in the US it was easier to leave NV behind and stand up new technology elsewhere and let NV be an island.
That said, none of those same handcuffs would apply to a company like Draftkings which doesn't have a license in NV. As newylewis pointed out, sometimes vig can differ based on the taxation policies that apply to a jurisdiction. For the most part, books don't regionally shade their lines though.
“Jack”
USA Gambling expert