I am grasping in the dark here; but I
think it is strictly a geographical thing. All VG is ultimately synthetic (it does not exist naturally) so source becomes more a matter of personal preference.
My understanding, from what I have read (meaning I could be 100% wrong!

), there is not a lot of VG still being produced in the United States. It is just not very profitable. So most(?) comes from elsewhere (Inda, is a big one). Some folks are concerned about sustainability practices in some countries; so source can be an issue.
But otherwise; VG is VG.
