The Tourist Police and other uniformed men

On this blog in Setpember/October 2007 I wrote about the tourist police: men in green who stand on street corners supposedly protecting the tourists or helping them in some way. Today I saw a big truck with a canvas roof that stopped on the corners and these green outfitted men hopped in apparently done for the day (it was 5:00). It's like a big army truck, open in the back w just a canvas stretched over for a roof. It's an interesting concept and I'm not sure what role they really play but there are many of them in this particular area along with apparent police officers (real ones). There are men in white shirts w emblems, the ubiquitous green-clad tourist police, and men in blue shirts w emblems and hats resmebling what I would assume to be 'real' police officers. I'm not sure how to differentiate them all except for the men in green. Oh, then there are men in orange jumpsuits who appear to give tickets to people or call them out on mistakes they make whilst driving. They wear what seems to be a leather lower back brace of some kind - - but they all wear them so it can't be for their backs.