what is a light rail vehicle?
A light rail vehicle is a form of public transport that operates along an exclusive right of way. It uses a steel tracked fixed guide-way and also has vehicles that are capable of operating as single unit. Read more at http://bombardier.com/en/transportation/products-services?docID=0901260d8000a536.
they're also not as heavy as frieght moving rail stock.
Public trams, like what they have in San Francisco, not sure where else in the States they are.