The top one is Retic Stingrays or Potamotrygon Reticulata. they get to be between 10-14 inches on average, some even larger. They are one of the best rays if you can afford to have anything above a 180 gallon. My 10 inch male has a thick tail, but my 8 inch female still has a whip type. The better fed they are the thicker the tail will become. I can't tell your bottom pic.