It depends on how big (or long) of a half shield you want. They are basically the same shield except the vr904 is smaller (or shorter) from top to bottom, meaning it covers less of your face.
That being said I prefer the smaller vr904, I like the way it looks on my helmet better. I wear one to protect my eyes and it does the trick.
My suggestion is try them on if you can that is the best way to decide.