W has much smaller noodles before they are cooked. After cooking for 8 minutes, they grow significantly.
W is much more starchy! Do not cook for only 7 minutes. Do not cook in a small amount of water that might seem normal to you. If you do those things (which I did at first), you risk making the pasta quite gummy with tiny hard things in it. My suggestion is to use even more than six cups of water (at least that much), and cook for about 9 minutes (maybe longer) instead of 7 to 8. Mine was pretty good that way.
W probably has the higher quality cheese packet. It's supposed to have natural food colorings and real cheese in it (but it is powder).
Over all, G is my favorite, and is faster/easier to cook. When cooked properly, they both have nice flavors, but are quite different. I do think adding extra salt does help the flavor of both W and G.
I don't know what the hard things are, but they feel like weevil larva exoskeletons when I bite on them. I did not see any weevils, though. The pasta is supposed to be best by some time in the future a long time from now. I did not notice any hard things from the box I cooked for 8 minutes (they seemed to have softened, if present, which weevils wouldn't). I noticed lots from the one I cooked for 7. I noticed about three from the one I cooked for 9.