Psychology alone is a social science. If you look at all college catalogs, psychology is labeled under "social sciences." It is considered a science since it is possible to do quantitative studies with statistics involved.
Behavior is only one aspect of psychology. It could be called a "behavioral science" but that would only cover one aspect of Psychology when it is really more to it. So when someone mentions behavioral psychology, it involves one branch of psychology that famous psychologists, Skinner, Pavlov, and Albert Ellis, have been involved in.
However, the term "Psychology" is an umbrella where different parts of psychology come under: social psychology, behavioral psychology, cognitive psychology, clinical psychology, counseling psychology and industrial psychology. It can go on forever.