How does one distinguish rheumatoid arthritis from any other kind or from unlabeled aches&pains?

Many ways. Ra has joint swelling and usually an hour or more of morning stiffness. Ra can sometimes have positive blood tests. If the wrists or large knuckles (mcp's) are swollen, there is a high likelihood you have ra.
Specific syndrome. Rheumatoid arthritis is a very specific syndrome with a certain spectrum of symptoms including joint pain. In addition there is blood work that can help confirm the diagnosis.

Related Questions

Any reason my upper arms ache so much to keep me up at night. No injury or strenuous exercise during the day either. I do have rheumatoid arthritis.

Yes! Immobility increases pain in inflammatory arthritis. Shoulders are particuarly problematic since we frequently sleep on them-pain wakes us. Make sure you take a long acting NSAID at supper, so you have adequate pain relief at night. Ask your doctor if mechanical damage to your shoulders is also present. Read more...
See below. This could be due to nerve compression from bulging disk. I would suggest talking to your doctor, or possibly visiting a neurologist to see if you have this problem. Read more...

early rheumatoid arthritis. Dr. has me taking 2 Aleve (naproxen) twice a day no other drugs yet. Is it safe to get flu shot without making joints ache more!

Flu shot safe. The flu shot is safe and MUCH safer than not being protected against the flu. Hope you are seeing a Rheumatologist because if you really have Rheumatoid Arthritis, even if early you need more than Aleve (naproxen) twice a day. If you are not seeing a Rheumtologist, please see one. Read more...