Here is a photo of a white heron, taken by Constance Mier on the main shoreline of Biscayne Bay National Park, near Miami, Florida, on May 25, 2012.
You can see more of Constance’s photos at her webpage: http://cmierphotoandfitness.net/myphotos.html
Yellow-crowned Night Heron
Nope, bill is too thick, eye too big, and Cattle Egret should have black legs
Little Blue Heron (immature)
No, bill is a little too thick, and Little Blue should have greenish-gray legs and bill, not yellow.
Sorry, Great Egret would be much more slender, and have black legs.
Great Blue (Great White) Heron
No, "Great White" Heron would be much more slender, and have drabber grayish legs and bill
Nope, Snowy Egret is more slender and has black or greenish legs, dark bill