I don't think med students see pt's. Im not sure about that. But residents are finished med school and they are doing residencys in different specialties to decide what they want to specialize in. Fellows have already decided what they want to specialize in and they work in that area to learn more. Attendings are instructors for the med school and work fulltime in the hospital.

The first two years of medical school are primarily classroom, although students are also introduced to the clinical setting during this time, attending rounds and lectures. The third year of medical school is primarily clinical. Third year medical students may attend to patients under the direct supervision of a resident or attending. While a graduate of a US medical school is entitled to be called "Doctor", obtaining a license to practice requires at least one year of post school internship. Interns work under the supervision fo residents and attendings, though not necessarily under direct supervivion. A resident is responsible for the actions of interns under their supervivion. Most students enter a multi-year residency program that takes anywhere from four years (Family medicine, anesthesiology) to as long as eight years (neurosurgery.) The first year of the program is a genral internship in which the doctor is rotated through various departments, or various hospitals, to get a general clinical experience. Attendings are doctors who have finished a residency and are employed by a hospital. Fellows are doctors who work in research, typically funded by an outside agency, and whose clinical work, if any, is done in conjunction with a specific research program.

As you might expect, a 1st year medical student is lower than a 3rd year. This is true for American allopathic schools (ones that give MDs rather than DOs). In most cases - Duke University being an exception - students receive training in "basic" sciences during the first two years, with the focus on "normal" and pathologic being the backbone of 1 and 2. Many students now are given clinical opportunities, either shadowing or directly contributing to patient care. A 3rd year student (sometimes called a clerk) works through most services in a hospital - surgery, medicine, pediatrics, psych - to expose them to different career options and to help put their classroom hours into context. They often still have classroom time. A 4th year student also primarily works with patients and may be treated like a "sub I" meaning sub-intern. Internship is the first year of residency, and residency programs (or the time a student actually specializes, since there are no "majors" in med school) last between 3 to 5 years. After the first year of residency, the student loses his/her "intern" designation and is simply called a resident. Sometimes you may hear residents being referred to as house staff, because they effectively live at the hospital. Now after a student has finished his/her residency, he/she can either go on to a fellowship (where he/she will be known as a fellow) or look for a job, at which case he/she becomes an attending physician. Sometimes a student will apply for another year of residency - not so much to be a student but to be a teacher. These people are called chief residents, and in charge of their less-experienced peers. Chief residents often do this to help them get a fellowship or teaching position in the future. There is a hierarchy with attendings, as well, and as you might expect, a department chief is more powerful (but not necessarily older) than the attendings below him/her...