But as always, definitions for these things are mushy, and many systems in the world straddle the boundaries between streetcars and LRT, if there is even a real one.
For example, the Boston Green Line system runs the gamut from subway, elevated, private ROW with no grade-crossings, median ROW with grade-crossings, to street running (since they run 2-car articulated trains, it's quite a scene to see 50m trains turning tight corners and sharing the street with traffic). The system certainly uses "LRT"-grade rolling stock that are double-ended, but they have loops and rarely ever use the other end. They have the capacity for signal priority but doesn't use it. Station interval ranges from 200 m on the street-running sections, to 500 m in the subway and median-ROW sections, to 1 km on the private ROW sections, and scheduling is timetable-based. Underground/elevated stations have ticket gates, ROW stations have a mixed POP/pay-at-the-front system, streetside stations are pay-at-front only. So, is this system a "streetcar" system, or an "LRT" system? Or does it matter?