The instant I saw this wallpaper, it immediately screams to me this. Both concepts are the same even though the executions are done differently.

Your wallpaper is good, but the way the feather is positioned makes it seems like it is floating in air instead of floating on the water. The only part in the feather that actually looks like it is floating on the water is the stem part.

I think it's because the feather looks flat that this happens, and after looking at the screenshot you provided, I can see why it looks flat because it looks that way in the screenshot. Except in the screenshot, it is lying on a hard surface. In yours, it is floating on water, a totally different surface, so it doesn't exactly look as though it is floating on the water.

The feather is done nicely, but it just looks flat. Perhaps, a curling-feel to the feather might fix that to make it have depth instead of having it look rigid and flat.The moon does seem out of place though, since it shouldn't be that close to the water's surface. It could just be me though. Anyway, don't take my criticism too harshly. I think you did a fine job. What I do like is the glowing circles, it adds a whimsical and magical feeling to the feather, which has a lot to do with the series. Good job incorporating clouds to the background. My only critique is in the feather. Good job.