There are also British/American English differences here.  My American Heritage dictionary (from 2000) says that "tram" is "chiefly British" for streetcar. I also remember growing up hearing my grandmother talking about how much she missed the "trolleys" (never "tram" or "streetcar") we had until the 1950s in my home town. (Today some of them have been converted into bike and hiking paths; since they don't follow streets, I can see why it would have been strange to call them "streetcars.") These days the only time most Americans see "lightrail" is at airports, and "tram" seems to have won out over the other terms, at least at these venues.