Hi ozarker, yes there are many distinct differences between osteo and rheumatoid arthritis the main one being that osteo is due to normal wear on the joint while RA is caused by an immune system reaction that causes the body to attack the joints.
RA can be tested for by looking at a few blood test markers. RA factor is probably the tell tale sign of classic RA but many people test negative for this while having high SED rates and C reactive proteins. These too can indicate RA. This is called sero negative RA.
To my knowledge osteo mainly affects the small finger joints initially and most severely. I am not aware of any tests that can be run for it but someone else may be able to clarify that one.
Post Edited (Don_D) : 2/16/2016 2:42:08 PM (GMT-7)