Thanks for the info....honestly, I'm not even sure what the difference is and I'm not even sure which one is in the pie at Bob Chinn's.....all I know is that it's totally worth the hassle/mediocrity of Bob Chinn's!! It's got coconut in it, and a layer of custard.
ETA: Okay, I found a pdf of a sample menu from the restaurant; it's actually called "Slice of Paradise Pie" and here's the description: "From the
Japanese island, Okinawa, this purple filling has a sweet macadamia nut crust topped with a coconut milk pudding & fresh whipped cream."
So I guess it is the Okinawa sweet potato.