Can you explain the difference between Icy Jade, Water Jade, and Glassy Jade?

Good question!  Simple answer - No Difference.  Transparent/Transluscent and primarily Clear Jadeite used to be called Water Jade or Glassy Jade.  Crystal Jade was coined as a commercial name for this Jade.  Today the name has evolved in common usage to become Ice or Icy Jade.  Here’s a great article by Eric Hoffman that further clarifies how Glassy Jade became Icy Jade.

Icy Jade
by Eric J. Hoffman, ASJRA Contributing Editor 

    What is icy jade? Jade that was left out too long in the winter weather? Or is it something rare and valuable?
     Newsletter readers know that nearly all jewelry jade is Burmese jadeite, one of the two types of true jade. (The other true jade is nephrite, usually seen as carvings and ancient Chinese artifacts.) The term “icy jade” has become more commonplace in the past few years to refer to Burmese jadeite of exceptional translucency.
     The important attributes of jewelry jadeite are color, texture, clarity, and translucency. The most highly prized color is “Imperial Green,” a deep emerald green imparted to the jade by chromium ions. Texture refers to the compactness and uniformity of the jadeite’s microcrystals; the finer the texture, the better (brighter) the polish the stone will take. Clarity is absence of distracting inclusions. And translucency refers to how much light can be transmitted through the stone. At its best translucency becomes transparency, the ability to actually read printed text through the stone. Exceptionally translucent (or even transparent) jade that is highly compact and free of inclusions is called “icy” jade, and commands premium prices in the jewelry trade.

    Years ago icy jade was referred to as “water jade” or sometimes “glassy jade” and was not considered especially valuable. In a triumph of marketing Christie’s introduced the sexier term “crystal jade,” which later evolved to “icy jade.”
    Unfortunately, most of these measures for jadeite are subjective and without strict definitions, unlike, for example, grading diamonds. This can lead to all kinds of exaggeration depending on the whether the dealer is buying or selling. One attempt to bring objectivity to measuring translucency is the six-grade scale introduced by Ouyang Qiumei in her book Jadeite Jade: a Stone and a Culture. On this scale icy jade (she uses the older term “glassy”) grades out as 1 or 2 (“transparent” to “very transparent”). Keep in mind that the thickness of the stone must be considered when evaluating translucency. The best defense for the prospective buyer is to see and handle as much icy jade as possible before making a purchase. And as always, the more reputable the dealer, the more likely you will be happy with the purchase