If we are here, trains can differ in another thing: the longitudinal forces they can withstand. The US, with its much longer trains, demands much higher values than is the standard in Europe. But Europe also has railbuses and some trainsets which don't fit that norm, and for that reason can't be put in a long train or 'bumped' by a shunter.

_{*Lunatic*, n.
One whose delusions are out of fashion.}