- Attending (This person is definitely a doctor, they are what we usually think of when we say doctor. Undergrad + Med School + Residency (depending on the field, fellowship))
- Resident (All of these people are technically doctors, they have an MD or DO after their name)
- PGY (INSERT #) (post graduate year) depending on how long their residency training program is this could be PGY 1 - 10)
- PGY 1 (these guys are the interns, they are the lowest of the low in the MD totem pole. They are first years that were medical students between 2 and 10 months ago and act fairly clueless for the better portion of the year)
- Medical Student (These people are not doctors yet, they DO NOT have MD or DO after their name)
- M4 (4th year student, operates at a similar level to a PGY1)
- M3 (3rd year medical student, fairly clueless but depending on how far along in their 3rd year are closer in performance to an M4)
- M2 (2nd year medical student. Still in the didactic learning years with minimal clinical exposure, have net to no idea what they're doing)
- M1 (1st year medical student. In their first year of didactic learning, little to no clinical exposure, has absolutely no idea what is happening ever)
I hope that little snippet helps give a better understanding of what all these weird letters and titles really mean.