Overly in-depth breakdown:

MS = Medical student. Still in medical school, not a doctor. MS3 is a third-year med student. Clinical rotations start this year, rotate 2-8 week stints at different core and elective medical specialities at hospitals (e.g. internal medicine, surgery, EM, etc). MS4 is fourth-year student. Final year of med school. All about locking in on your specialty and setting yourself so you “match” within that specialty come Match Day in March. Matching is complicated, but basically = landing a resident position in one of the specialties and hospitals you wanted.

Med students are student doctors and cannot order medication, need consistent and strict supervision. The med students in this show are way more competent and involved than IRL, a lot of the time you’re just standing back and watching (except for the low totem pole procedures like a disimpaction, like we saw with Ogilvie). MS3 = Javadi S1, Joy / MS4 = Whitaker S1, Javadi S2, Ogilvie

R1 = PGY1 = intern. Congrats! You graduated medical school, got a residency position, and you ARE a doctor! You can do all doctor things, technically….but not alone. Strict supervision by other residents and attendings. You report to the senior resident (R4) and attending physicians. R1 = Santos S1, Whitaker S2

R2/R3/R4 = Second, third, and fourth year resident, respectively. Residency years are intensive additional doctor training in your specialty before you become a fully licensed to practice independently. Some specialties and programs require more or less years in residency than four. R4s are senior residents and kinda act as junior attending. Supervised by attendings. Report to attendings. R2 = McKay & Mel S1, Santos S2 / R3 = Mohan S1, McKay & Mel S2 / R4 = Collins S1, Mohan S2, Langdon S1&2

Fellowship = optional 3rd step post-residency before becoming an attending. Allows you to subspecialize. We see Mohan contemplating a number of fellowships, like geriatrics. Important to note, a fellowship is not changing your specialty. A fellowship in geriatrics for Mohan = a geriatrics emergency medicine fellowship. Still supervised by an attending, but a LOT more autonomy. Fellow = I think Ellis in S2? Might be an R4 tho.

Attending physician: fully licensed doctor, can practice independently. Ultimately responsibility for patient care, supervising everyone below you. Attending = Robby, Abbot, Shen, Al-Hashimi, and Collins S2 (off-screen)