XR250 and XR400 similarities

[Bossies]

So considering the strong recommendation to taking two of the same bikes if you are touring as a couple, what are the similarities between the XR250 and the XR400 for say a 98 model...other than the one has a bigger engine.

Do they share the same: levers, cables, filters, bearings, chains & sprockets, forks, frame?

Even if you take exactly the same bikes; if something goes badly wrong with the engine there is nothing you can do except order in new parts so there is therefore no difference if the bikes are slightly different but have common general spares as above...or not?

I note that they both share the same Haynes Manual.