"White Windy" exists in the same way that "white Blue Belle" exists . . . There are definitely some Windys who are paler than other Windys, but they are not "white" in the same way that Majesty or Glory is white. They were meant to be lavender.
One thing to remember about Windy is that she was ALWAYS a very pale lavender color without much hue compared to, say, Heart Throb or Lickety-Split. Though I do suspect some of the "whiter" ones have had some of their pigment leach out over the years.
But I've also seen Windys on eBay that the sellers claimed where white when in fact they were just a plain, ordinary Windy who wasn't even faded.