It happens frequently. My wife will wince or say "ouch" and someone will say..."what's wrong?"
"I have RA," she responds.
"RA? What's that?"
"Oh," comes the response, "I have arthritis." This is typical, yet expresses the ignorance of people in regards to one of the most insidious and debilitating diseases. Though I'm no physician, I will try and explain why except in extreme cases of osteoarthritis, its effects pale in comparison with RA.
Rheumatoid arthritis is an auto-immune disease, that is, it's an overly-energetic immune response of the body, which actually begins attacking itself. It's about one tenth as common as osteoarthritis and can affect young people as well as older people. Every single joint in the body can and usually is affected at one time or another. Some days it might be the knees are worst, some days the elbows. Sometimes the small joints in the jaw or where the ribs connect to the spine or sternum are inflamed. It is a progressive disease which can affect not only the body's joints, but other organs of the body, including the lungs.
Osteoarthritis is the "wear and tear" type of arthritis and generally occurs in those over 60. This type of arthritis has nothing to do with the immune system, it is caused by overuse of a joint, and usually begins in one joint. For example, when I had my knee surgery back in the 1980s, the doc told me I had the arthritis of a 70 year old man in that knee. I was in my twenties at the time. Thankfully, that arthritis hasn't really been much of a problem since the surgery. To be fair, this type of arthritis can end up being severely debilitating in some people. From the website Rheumatoid Arthritis Diagnosis: "Rheumatoid arthritis is a more severe disorder due to systemic
involvement, which may produce complications such as, pericarditis…
pleuritis… vasculitis, etc., causing a shorter life expectancy if not
diagnosed and treated properly."
About 1 in 10 have osteoarthritis, while RA affects 1 in 100.
Here is a video that explains some of the differences between the two types of arthritis: The difference between osteoarthritis and rheumatoid arthritis (RA)