Both actually. POTS is one of the most common forms of dysautonomia. An estimated 1 million to 3 million Americans have POTS - 75 to 80% are female. See our What is POTS page for a more indepth description. Further...an estimated 70 million world-wide have been diagnosed with some type of dysautonomia. It is not rare. Dysautonomia is a blanket or umbrella term that covers several different "dysfunctions" of the autonomic nervous system.
In very simple terms - your nervous system controls the automatic functions of your body (sleep, digestion, heart rate, blood pressure, saliva, sweat and so on). When these functions begin to fail or becomes dysfuntional - you have some form of dysautonomia. Often people with lupus, sjogrens, diabetes, celiac, MS, parkinson's, and rheumatoid arthritis have some form of dysautonomia or dysfunction of their nervous system. See Dysautonomia International's description here...
If you google dysautonomia, you come up with lots of complicated descriptions - and after seeing 9 different doctors without an answer as to what was going on with Meghan, I started doing my own research. The nervous system is very complicated and recent research has been key to understanding much of how it interacts with everyday body functions.
Sometimes I wish simplier words could be found to label these types of disorders. The minute I say "dysautonomia" or "postural orthostatic tachycardia syndrome" to someone, their eyes glaze over. It's like describing a complicated calculus problem to someone who freaks out when they hear the word math. I am hoping my blog can help simplify some of the complicated concepts - which I struggle to understand myself.