I don't think anyone knows except for the two suppliers for sure, so that being said, I've only had one of the two, but from the what I've read about the effects of both, I would venture to say it's very similar. I can't believe Tonga has as much of a bustling kava industry as Vanuatu so the amount of variation/accessibility of a wide array of cultivars will probably be much lower (at least compared to Vanuatu).