Three varieties of Dragon Fruit / Varieties of Pitaya Fruit exist
All varieties of the dragon fruit plant are vine-like cactus which yields a triangular cross section when cut perpendicular to the direction of growth. All three varities of dragon fruit cactus flower at night, growing best in moderate climates.
White Fleshed / Pink Skinned: Hylocereus undatus
These are perhaps the most common variety of the three varieties of dragon fruit cactus and are slightly to significantly less sweet than the pink or red fleshed pitaya fruit.
White Fleshed / Yellow Skinned: Selenicereus megalanthus
Generally the sweetest of the three varieties of pitaya, and with smaller sized fruits.
Colored Flesh / Pink Skinned: Hylocereus polyrhizus
Of the two pink skinned varieties of pitahaya, the sweeter. Yielding fruits larger than those of the yellow skinned dragon fruit (with fruits up to more than 2 lbs in weight).