I'd say as a North American, the big difference is the "no escape" room thing of some narrow, winding, poor line of sight UK roads--hedges, or hard grass berms, that are unnerving because you know you can't physically bail if a truck lorry comes up behind you quickly at the same time as an incoming truck lorry, and the drivers don't have the space really to do much. Or a car pulling a trailer, a retired gent in a rental rv , that sort of thing that happens once in a while.

Not having a bail out generally gets my spider senses tingling. I had motorbikes back in the day too, and it's always good to listen to your (, hopefully good) instincts of increased danger.

Over here we tend to have more room on roads, shoulders are often good, but it's really really rare to have UK style , absolutely no shoulder no escape room type roads, and when we do, it's for short distances.