Great post excaliber.
I'll try to explain.
1. Rounds vs No Rounds
Rounds are a daily activity where a physician or team of physicians + allied health professionals walk around and check in on their patients. While rounding, the physician will elicit from the patient, nurses, charts etc new things that have happened since the last time they were rounded on. It is very common in academic centers for these to be a teaching exercise since rounds are where many if not most decisions are made regarding patient care. Any physician that admits patients to the hospital will round.
Rounders: All admitting inpatient services, including but not limited to, surgeons, IM, Peds, Neuro, Psych, and OB/Gyn.
Non-Rounders: Anesthesiology, Pathology, Radiology, EM and physicians that work exclusively or almost exclusively outpatient including, IM, Peds, FM, Derm, etc.
2. Clinic vs No Clinic
Anyone who follows up with patients as an outpatient will have clinic. This is somewhat of a continuum since not all clinics are the same. Some people will exclusively see patients in an outpatient clinic, some will never see someone in an outpatient clinic.
Heavy Clinic: Outpatient based IM, Peds, FM, Derm
Variable to light clinic: Surgeons, Neuro, Psych, OB/Gyn
No Clinic: Radiology, pathology, anesthesia, EM
3. OR vs No OR
Self explanatory, surgery vs everyone else.
4. Procedures vs No Procedures
Surgery plus less invasive tests including, but not limited to interventional radiology, heart caths, scopes, dialysis access work, ECT, Bronchs, lumbar punctures. Most non-surgical procedures are simply IM sub-specialties that have their own fellowships. For instance to be able to do heart caths, one must do IM (3y) + Cardiology (3y) + Interventional Cardiology

.
Procedures: Surgery, IR, Int Cards, Int Nephro, GI, Pulm/Crit care, Derm, OB/Gyn, EM
No Procedures: Everyone else, although even FM or others will sometimes perform minor procedures depending where you are.
5. Patients vs No Patients
Direct vs. indirect patient care
No Patients: Pathology, Radiology
Patients: Everyone else.
6. Chronic Care vs Acute Care
How long do you see your patients for? One/Two visits or more? There is quite a lot of variability within single specialties. Things like EM or anesthesia are the obvious acute care. The obvious chronic care would be Heme/Onc, IM, Peds, Surg Onc, Vascular Surgery etc.