What's the difference between tendonitis and arthritis?

Completely different: Tendinitis is inflammation around the muscles and tendons that may cause pain, often from overuse or compensating for a weak muscle. Arthritis is defined by inflammation within a joint such as the knee. Osteoarthritis is an example of arthritis where the cartilage cushion is worn down, causing pain and stiffness.

Tendon not joint: Arthritis by definition is inflammation in the joint. The tendon helps attach muscles to the bone. When a tendon is inflammed, swollen, and tender it is called tendnonitis. Both are describing inflammation but at different locations: the joint verses the tendon.

Tendonitis: Tendonitis is inflammation of a tendon. A tendon is the part of the muscle that attaches to the bone. An example would be tendonitis of a rotator cuff tendon in the shoulder. Arthritis is inflammation in a joint. Examples would be osteoarthritis of the knee. Hope this helps.

No, can be the same!: Tendons attach to the joint capsule or bone. Tendinitis is a basic form of enthesophy (which also includes ligamentous and periosteal inflammation) is basic feature of the most common inflammatory arthopathies, spondyloarthritis. Inflammation of tendon sheath is common in ra.