A portrait is a painting, photograph, sculpture, or other artistic representation of a person, in which the face and its expression is predominant. The intent is to display the likeness, personality, and even the mood of the person.
up close and personal
Close-up portraits feel more intimate than standard portraits. Some say it can capture the inner beauty of the subject.
Full body portraits take much more work because the background comes into play with the subject. Helps tell the story of the subject with symmetry and anything else your setting can provide.
The standard portrait to me is a mix of it all. Trying to capture the subject as well as possible without using their entire body or wide shots but still being able to get an understanding of their environment.