What is osteoarthritis? rheumatoid arthritis?

They are different: Rheumatoid arthritis is a systemic autoimmune disease that attacks the soft tissue and cartilage in the body's joints. It responds well to specialized, autoimmune meds but can require surgery. Osteoarthritis is a mechanical wearing away of the cartilage. It is not systemic disorder. It can respond well to the more commonly known anti-inflammatory meds. It too may require surgery.

Different arthritis: There are over 100-150 different types of arthritis, maybe more. These are two separate types of arthritis. Rheumatoid is an inflammatory type of arthritis, with inflammation in the joints and actually in other areas of the body. Inflammation has leukocytic infiltration, redness, heat, capillary dilatation, and pain. Osteoarthritis is more like wear and tear arthritis - mechanical type

Osteoarthritis-: Can develop from many factors, including systemic inflammatory arthritis. My patients with RA or AS frequently need hip replacement because cartilage loss do to inflammatory damage to their cartilage! The discussion is not between either or or!

Yes you could: But it is very hard separate one from the other.