like acep vs aaem vs emra etc... this is confusing
They aren't boards. The only boards of emergency medicine in the US*: the American Board of Emergency Medicine (ABEM) for the MDs and the American Osteopathic Board of Emergency Medicine (AOBEM) for the DOs. The other national organizations are:
ACEP: American College of Emergency Physicians. The largest of EM professional organizations, aims to be every emergency physician's organization, but also to represent the specialty as a whole, including other interest groups which are sometimes in conflict with EPs. However, ends up being more relevant to community physicians more than academics. Leadership has been heavily influenced by CMGs (big business EM). Holds a conference every years that's like 50% CME, 40% industry stuff, 10% research (misleadingly called "Scientific Assembly").
AAEM: American Academy of Emergency Medicine. The smaller of the two general professional organizations. Aims to be ACEP's rival and represent all emergency physicians. Their policy statements are more closely in line with what the majority of folks on this forum believe in. Given that they are smaller and have less money, they also have less influence. They hold a conference similar to ACEP's, but it's smaller.
SAEM: Society for Academic Emergency Medicine. As the name suggests, they are for academic physicians. Their efforts are largely directed at research and education and their annual conference is more like 40% education (not CME, but like workshops on how to be a better educator), 40% research, 20% industry stuff. They are influential but only on the nerds. They aren't aiming to be everyone's org.
CORD: Council of Emergency Medicine Residency Directors. For PDs and APDs. Mostly interesting for people in that career track.
EMRA (Emergency Medicine Resident Association): ACEP's student/resident arm
RSA (Resident and Student Association): AAEM's student/resident arm
RAMS (Resident and Medical Student Association): SAEM's student/resident arm
But
@namethatsmell's explanation is basically accurate
*There is also American Board of Physician Specialties (ABPS) that offers Board Certification in Emergency Medicine (BCEM) to family physicians who complete a two year fellowship. It is the view of most people on this board, and in my estimation the opinion of most US emergency physicians, that this is not really a real board. ABPS is a competitor to the ABMS and generally only pursued by people who for some reason can't be boarded through an ABMS recognized pathway.