When under the care of a physician, receiving treatment in the ER, or establishing care with a PCP, most people don't ask the physician what degree they have. In fact, many non-medical people and patients are entirely unaware that in the US there are two different medical degrees, MD and DO, and two different paths to becoming a physician. Here are the major differences (and similarities!) between the MD and DO degrees.
As an osteopathic tutor at Med School Tutors, I have had a ton of experience with students preparing for the COMLEX. Through my own testing experience and the experiences of my students, certain examination topics have come up so many times that I tend to refer to them as “COMLEX canon”. This canon of core topics is broad, but unique to the COMLEX among the topics is OMM.
In short, yes. The COMLEX is different enough from the USMLE in enough ways that a dedicated question bank (QBank) is necessary.