The Snowy and Great Egrets are also easily seperable by bill color, an identification cincher in many more situations than the yellow feet of the Snowy. The Snowy has a black bill with yellow lores while the Great has a yellow bill with green to yellow lores. Once you have a little experience with both of these species the size and habits of the birds' will result in a quick identification.
The more troubling identification problems come from the juvenile plumages of Little Blue Heron and Snowy Egret. Both of these birds are very similar in size. The key to this identification is all in the leg and bill color just as the identification between the Great and Snowy Egrets. The Snowy has a pale yellow bill with a black tip while the Little Blue has a grayish bill with a black tip. The legs of the Snowy are pale yellow (similar to the color of the bill) and usually have some black mixed in throughout the legs. The Little Blue's legs are pale yellow-green and never has any black on the legs at all.
There are many more species that can cause a problem that I will write about in the next few days. If you have any IDs that you struggle with let me know and hopefully I will be able to help you out.