Some of the symptoms can overlap - but a good Dr should be able to figure it out by documenting all symptoms and then sorting them out.
RSD-
Extreme skin sensitivity - to air/breezes{ hot or cold}/ touch/fabrics
obvious skin changes & swelling, color changes {reds, blues, purples}, blotchiness

I'm just going by what I had read on websites and the forum discussions- I don't have any first hand knowledge of RSD.

RSD can affect any part of the body while TOS mostly affects upper body - after years may begin to spread due to myofascial components {IMO}

RSD does affect bone density ??- I think that is in the severe stages or after long term of having it...