The picture on the left is from Fremont, California (Dec 2011) and the one on the right is from Redwood City, California (Feb2012)
I think the one on the left is a Great Egret as it has yellow/orange bill, black legs and is fairly tall. I think the one on the right is a Snowy Egret as it has a black bill/yellow eye area and yellow/black legs and is somewhat small.
Have I got my Egrets correct, or is there another type they could be? Are the more reliable identification traits to distinguish between the two or are the bill, legs and size pretty reliable?