They are all herons! From the small bittern heron on the tree branch, to the mid-sized white heron, to the large blue or tri-colored heron -- these birds all belong to the same species. Their feet and legs may be different colors, but that sharp beak and those intense eyes are a clue that you're looking at a heron.
Herons don't swim, but they largely live around lakes and dine on fish and other aquatic animals that they stab with their beaks while standing motionless on the shore, waiting for their prey. They build nests high in trees, to keep their eggs safe from predators, and they usually stay with the same mate. The pair most likely live in a colony with many others, including differing bird species.
These are just a few of the 64 different heron species I've photographed. Once you spend time with them, you begin to see differences in personality, approachability, and general behaviors, and you can even begin to differentiate one bird from another.