Name: Dave Paul Puna, HI (Zone 10b) Live in a rainforest, get wet feet.
Butter Beans are in fact a type of Lima Bean, Phaseolus lunatus. Check out the links.
I eat Butter Beans regularly, but being a diabetic, I don't eat butter, which many recipes include. Butter Beans / Lima beans are a great food for diabetics, as they don't cause the blood sugar to raise very much.