Found an old pdf on the difference between the tour and the tour sport and see there is only a few hundred grams difference in weight but that makes a huge difference in strength
It's not just the weight, the geometry is slightly different and the Raven Tour has clearance for wider tyres. I use 50 mm width on mine, but I think it is possible to go up to 55 mm and still fit mudguards.
If buying now, the drawback of the Raven/Raven Sport Tour/Raven Tour frames is that they are all designed for 26"/559 tyres, which seem to be going out of fashion. The current Nomad model is designed to use any of three sizes - 26"/559 or 27.5"/584 or 29"/700C/622.