What tests are used to differentiate between MS and Lupus?

I have had a very mild case of MS for 15 years. Or so I thought until I began feeling extreme fatigue and aching in my joints and leg muscles along with minor migraine headaches. MRI showed lesions consistent with MS, but bloodwork showed high positive anti ds-dna along with positive ANA. Neuro says the DS DNA is pretty specific for lupus and that migraines and joint pain aren't symptoms of MS. I'm waiting on the spinal tap results which the neurologist says would show ogli-bands in cases of MS. Don't these bands show up in Lupus too? I'm wondering what other test they can do if the spinal results are unremarkable for either disease.