Welcome back, in your absence, we've had this discussion several times, so some of this will be repetition.
I doubt there's much difference between the Raven and the Raven Tour. Is there any? Or was the "Tour" prefix just dropped when the "Sport" model ceased production?
The Nomad is a bit heavier, how much I don't know, I'd guess less than half a kg, and wouldn't be surprised if it was half that. It isn't the sort of weight difference you'll notice if carrying it upstairs. it isn't the weight difference that's important, it's how that alters strength and feel. If you forget the weight and get the bike designed as closely as possible to your intended usage, it'll be the right bike and the right weight.
Consider the difference between sizes of the same model is likely to be greater than the difference between models of the same size.
Edit - Remembered I had this bookmarked, the 2011 Thorn Raven brochure
https://www.yumpu.com/en/document/read/11943898/raven-tour-and-sport-tour-brochure-spring-2011-thornPage 8 might be of interest, it details how different the Tour and Sport models are, also that the weight difference is 200g for the frame and 120g the fork.
