There isn't any real difference other than the name. All a control valve can do is close and open by a certain amount, thereby increasing or decreasing the pressure drop across the valve when flow is present. That's it. What causes it to close or open is dependant on its control feed or feeds. In you case they all seem to be pressure related, but it could just as easily be flow, level, temperature or any other variable, sometimes lots of variables and the control system picks the worst one to control on. Each process will require a different thing or things for the valve system to control on.
does this answer your question?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
Littleinch is correct (as usual), but please in addition bear in mind that local 'slang' or un-official naming practise around the world and in single plants and places will slant the three different namings to include or exlude anything or any valve-type without any real sense.
Therfore: ask suppliers, endusers, producers when in doubt. There are always a multitude of products and ways of solving each single regulating/reduction/control task.
Its like naming a control valve a flow regulator or a pressure regulator. The valve donsnt know this - its just a valve.
But wrt. to naming philosophy i would consider naming a valve a pressure reducing valve if its purpose were to maintain a steady downstream pressure by restricting the flow rate and a pressure regulating/controlling valve would control the upstream pressure pressure (in the same way).
But "being a man of the world" ;-) i accept that just about half the population of said world would have the exact opposite oppinion (and not inclined to change)
