United States Medical Licensing Exam/
Comprehensive Osteopathic Medical Licensing Examination
=USMLE is for allopathic medical schools (MD)
=COMLEX is for osteopathic medical schools (DO)
BOTH are medical schools that require medical licensing exams. They test the same concepts, basic sciences, clinical information, but the COMLEX has an "OMM portion" that requires knowledge of osteopathic manipulative medicine (emphasis on musculoskeletal and function-structure "physical therapy"). Each exam consists of 3 different tests known as "Step 1, Step 2, and Step 3".
If you are a med student, you have to take either the USMLE/ COMLEX test. "After finishing the 1st 2 yrs. of med school, I have to take Step 1, and then one yr. later, I have to take Step 2, and then right before I graduate, I have to take Step 3. Sheesh...that's a lot of tests and money!!"