The COMLEX fires out disparate pieces of info, often in poor context, and expects the examinee to draw a conclusion. I also think the COMLEX requires a reliance on likelihood more so than the USMLE, i.e. success in answering a question often relies on looking at the exam’s notoriously terrible questions and being able to make an educated conclusion based on available answer choices, likelihood of a disease state, and a gestalt for what the question writer wants, or even finding and recognizing a single relevant factoid. I sometimes feel like the COMLEX is a “feelings” exam where gut instinct matters quite a lot. I would agree that it is the “harder” exam, but only in the context of pure stamina and frustration. You can draw your own conclusions about why the COMLEX is like that, but it probably comes down to some combination of available resources and a desire to create an exam that best reflects the “everyday” nature of information gathering on the wards. Medicine doesn’t have a vignette to slowly (and tediously, in the case of some USMLE questions) walk you through the patient presentation. You assemble pieces of info and try to recognize patterns.
In contrast, the USMLE wants to know how much and how detailed you know a subject. It’s probably a better test of your raw medical knowledge because it really flexes the details of a disease process. Another advantage of the USMLE is that it tends to stick to the script. It’s rare to encounter a truly terrible question, meaning you could typically find it somewhere in a known review source. With some exceptions, not knowing an answer is probably a reflection of some failing in your studying or learning. This one feature is why most people who take both call the USMLE the “fairer”, or better, exam. It's also why USMLE scores tend to be a direct result of how well you did during the preclinical years, the amount of time dedicated to studying, and the number of review questions (read: simulation) you completed. The COMLEX will straight up ask you random craziness, including details that some professor ranted about in class and you ignored at x 2 speed.
The COMLEX is also known to harp on certain subjects, which means that having an unfortunate weakness in your medical knowledge can be magnified out of proportion on test day. DO students will talk about having exams heavy in a few areas. This occurs in a way disproportionate to the USMLE. If you have a strength in that particular system, I’m a big believer that it definitely results in a boost come test day. This is probably why people routinely observe actual scores that are significantly higher or lower than the COMSAEs. I also think this is one, among many, explanations for the DO students who have high USMLE scores disproportionate to their COMLEX and vice versa. During the preclinical years, I remember faculty at our school occasionally reporting that some subjects were notoriously overrepresented and our school was big on highlighting these during the first two years. If you paid attention, you probably knew not to slack on those particular items, but it was unfortunate for those students with a particular weakness in grasping those subjects.
The exams are similar but different, mainly in the question style. The material is clearly the same, because high performing students routinely report solely studying for the USMLE, refreshing OMT, and then taking the COMLEX a few days later to good effect.
