Have a look at this interior. (Click, as always, to enlarge.) Can you tell if it's a bus or a streetcar/tram?
I photographed it at Porte de Choisy on the south edge of Paris, where it's about to begin a run deep into the southern suburbs.
Look again at the interior above. Note details like the ticket readers next to the first set of doors. (The one on the left is for the new Navigo smartcard, the other for standard magnetic tickets.) Note, just visible in the upper left of the photo, a strip map showing every stop that this bus makes along its route. Note the whole look and feel.
As I observed last year in Germany, European systems present buses and trams as part of a unified system, with amenity choices that minimize the difference between the bus experience and the tram experience. This is a striking contrast to US "streetcar cities" such as Portland and Seattle, where the streetcar is as differentiated as possible from the bus system, as though it's expected to serve a different clientele.
Next to the bus at Porte de Choisy is a "tram" stop, the T3, which runs along the whole southern edge of Paris. I should really call this light rail, as it has most of the features Americans would expect for that brand: All exclusive right-of-way and signal priority, so that stations are the only reason it stops. Here's the vehicle, by Alstom. It's a snake: a continuous vehicle with six hinge points and seven articulated sections.
The continuous open space is wonderful. But there's nothing else about this design, in terms of overall level of amenity, that differs from the bus. (And on a hot day in Paris like today, both are vastly more pleasant than the older lines of the Metro, which lack air conditioning or even much ventilation!)
This vehicle isn't trying to serve different people than the bus serves, or to provide a higher quality experience. This vehicle is on rails for one good reason: The corridor it serves needs huge capacity -- many passengers per driver -- and only a light rail vehicle can provide that. But for the same reason, it's designed to a high reliability standard: separated from traffic in a grass-tracked median, able to pre-empt many signals, it seems to encounter no delay apart from the stations themselves.soon here on the remarkable parallel improvements in Paris's essential bus system. But for now, just notice that in Paris, light rail is just what you do when you need a really, really long bus. Other than that, there's an attempt to make the bus and rail experiences as similar as possible. Both are clearly part of the same system, aimed at the same diversity of riders.