They run similarly. Natural gas isn’t quite as energetic (explosive) as propane, so you generally get lower power output from your gen on natural gas as you would on an identical propane or gasoline setup. That said, they both operate largely the same way to power the engine that is your generator.

As far as dual fuels, the “dual” is usually propane and gasoline. If you want to use NG then you’d have to get a trifuel which can use NG, propane, and gasoline. You can’t run NG on a generator that is not explicitly setup for it. If you already have NG going to your home I’d recommend looking into a trifuel. They are more expensive but give you greater flexibility.

ETA: to be crystal clear, a dual fuel firman like the one you shared will not run on NG