Metro, not light rail. Light rail is an ambiguous anglophone North American term (because anglophone North America kind of sucks in transit) that can mean anything between a tram and a mini metro, but it's wholly inappropriate for BART and for the Movia trainsets.

Also, it's kind of by luck - BART uses the so-called Indian gauge, and Movia trains have been acquired by Indian cities for their metro systems, so Bombardier/Alstom already had everything in place.