well for the most part, we bahrainis usually stick to a plain white one
and saudis usually wear the red/white ones.
as for the black/white, green/white, grey/white....etc i dont know where they originated from, but i only seee them being used in Jordan and neighboring countries
and no these colors do not symbolize any different meanings, this garment, as someone pointed out, did originate centuries ago with the purpose of protection agaist sand, sun, cold...etc, but now its primary use is one of heritage fashion.
hope that answered your question