Understanding Auxiliary Branches of Military

I've been trying to do some research into potential paths after graduation and came across the term 'auxiliary branches' in the military. I'm a bit confused though, what exactly does this mean and how do they differ from the regular branches?

Auxiliary branches can refer to organizations that assist, support, or affiliate with the main branches of the military, which are the Army, Navy, Air Force, Marines, Coast Guard, and Space Force.

One of the key differences between the main branches of the military and their auxiliaries is that auxiliary roles are often composed of volunteers who do not undergo the same stringent training as those in regular active duty forces. These organizations will often have specific roles that they fulfill.

For instance, the U.S. Coast Guard Auxiliary is a volunteer organization that assists the Coast Guard in its non-military and non-law enforcement missions. Members conduct safety patrols on local waterways, assist in Search and Rescue, teach boating safety classes, conduct free vessel safety checks for the public, and more.

Similarly, The Civil Air Patrol (CAP) is a congressionally chartered, federally supported non-profit corporation that serves as the official civilian auxiliary of the United States Air Force (USAF). CAP is a volunteer organization with an aviation-minded membership that includes people from all backgrounds, and walks of life. It performs three congressionally assigned key missions: emergency services, which include search and rescue (by air and ground) and disaster relief operations; aerospace education for youth and the general public; and cadet programs for teenage youth.

Keep in mind that each auxiliary branch is unique in its duties and roles which support the main branch it's affiliated with. Some auxiliary groups may require a certain level of training appropriate to their tasks, but it generally isn't as rigorous or encompassing as the training that active-duty service members receive. The ability to volunteer and serve part-time is a significant factor that differentiates auxiliary service from regular military service.