The distinction between a heron and an egret is vague. It depends more on appearance than biology. A clue is that the word "egret" comes from the French word "aigrette" that means both "silver heron" and "brush," referring to the long filamentous feathers that seem to cascade down an egret's back during the breeding season.
Egrets are in the order of Ciconiiformes that consist of large, long-legged wading birds. The 10 species of egrets are listed below. Photographs are included for those high lighted in red.

Great Egret or Great White Egret, Ardea alba
Intermediate Egret, Ardea intermedia or Egretta intermedia
Cattle Egret, Bubulcus ibis
Little Egret Egretta garzetta
Eastern Reef Egret, Egretta sacra
Western Reef Egret, Egretta gularis
Snowy Egret, Egretta thula
Reddish Egret, Egretta rufescens
Slaty Egret, Egretta vinaceigula
Chinese Egret, Egretta eulophotes