Having had RSD for so long, I've met many with both RSD, and MS. My Neurologist specializes in both. I think that they have similarities, but are very different.
For instance, I've never heard of MS being induced by a trauma.

It may be like comparing a migraine with a tension headache.
Both effect the head and cause pain, but they're different, and so are the treatments.

So it goes with RSD and MS. In my humble little opinion, anyway.

Be well,

ASB