Yes there is a clear difference in my dialects of English (Scottish and Standard Southern British).
Anything that is there specifically to indicate the road layout is at
traffic lights, roundabout/traffic circle, traffic signs, road markings
but anything there for any other purpose it is by
street lights, advertising signs, trees, houses
I think the difference is that the first category are in the exact place by definition, whereas in the second the proximity is arbitrary.
Some dictionaries, e.g. GPC, don't list goleuadau as the plural of golau. It seems that golau is the sort of light that does not usually have a plural anyway, such as the light shining through the window. Goleuad seems to be the actual device for making light, formerly known as a lamp. Since neither golau not goleuad is given for English lamp, I think goleuad must have taken over from lamp and erllau in Welsh at the same time as light took over from lamp in English. If anyone knows better, please let us know.
That's what I gave, and it was accepted without even an alternative being offered.
Certainly it is always lights in the UK. I don't know if anywhere else is different, but they are fundamentally plural as they generally come in sets of three (red, amber and green) and are then usually found in even bigger groups as you have at least one set of three for each direction of traffic. When you wish to refer specifically to the lights at one junction you usually refer to a set of lights.
(Note that if anyone finds amber unusual, this is the official term on British roads. Increasingly people say orange and the correct term on the railways is yellow or caution.)