Today's Light Rail "Systems" are probably more like the old Interurbans than they are like the typical city streetcar lines. Most Light Rail Lines have some PRW, operate somewhat faster than the old streetcar lines did, and, has been mentioned, often use train operation, as opposed to the single units operated by most of the old city streetcar systems. Of course there are exceptions to everything, the suburban SEPTA Routes 101 & 102, ( the former Red Arrow rail lines) are considered Light Rail Lines, especially in light of their present Kawasaki equipment, but generally operate single unit "trains" ( with some two car rush hour trains) and the city versions of the Kawasaki's, used on the Subway Surface Lines are considered LRV's, though the lines over which they operate are nothing more than the last remaining city streetcar lines ( along with the all surface Route 15)in the city.
Where these lines differ from the old Interurbans is in their terminal points, with most connecting points in the same Metropolitan Area, rather than two towns or cities at least ten miles apart. Thus, Baltimore's Central Light Rail Line could be characterized as an interurban, except for the fact that most of its run is in Baltimore City, even though its southern end ( between Camden Yards and its Cromwell Station- Glen Burnie terminus) uses the ROW of an old interurban, the Baltimore & Annapolis Electric Railroad.
Many of the old interurbans, particularly in the mid-west connected places as much as 200 miles apart ( Ohio's old Cincinnati & Lake Erie RR connected Cincinnati with Dayton, Springfield, Columbus and Toledo--- and for a brief period circa 1932, ran service all the way to Detroit), and some of the "better" properties rivaled the Steam Railroads in providing such services as dining cars, porters, and in some cases, even sleepers. Light Rail Lines are, as has been indicated, generally confined to a single Metropolitan Area and do not provide any form of luxury services.
Please Move to the Rear and Speed Your Ride
( Philadelphia Transportation Company)