There are two major types of Graduate Studies in the United States: Master's and Doctoral levels.
Academic master's degrees:
There are two types of bikes Master's programs: Master of Science and Master of Arts and usually extends both qualitative to two academic years and a mixture of lectures and practical work and research. And can be up to attend lectures and practical work required between 30 and 60 hours of instruction. In addition to dissertation and/or oral test. And can lead master's degrees such studies to PhD level directly.
Professional master's degrees:
Usually lead the professional master's study to a particular profession, not to doctoral studies. This includes MBA (Master of Business Administration), and MED (Master of Education), and MSW (Master of Social Work), and MFA (Master of Fine Arts) and so on. Usually these programs require 36 to 48 hours of classroom and do not require a thesis.
PhD studies in America:
The doctoral degree or PHD is the most common, which require students to provide an important original research and writing a thesis and discuss their work successfully before a panel of professors at the university. It may take the full period to complete doctoral work between five to eight years. It should be noted that the professional doctoral degrees, including the EDD (Doctor of Education) and DBA (Doctor of Business Administration) involve a combination of practical work and attend lectures and research.