Post [Q] S4 Back Covers?

It has come to my attention that there a a range of different covers for the S4, I do not mean colours or carrier printing but rather, some have no printing at the back and some have 'Galaxy S4' printing. Also the i9506 (4G) models vary from having the 4G print at the back to nothing at all.

Does anyone know why this is or whats going on?

On another note, has anyone ordered from TopBuy before? I purchased the i9506 from them, it is yet to arrive but I'm becoming anxious as to whether or not I will receive a genuine model. TopBuy claims that "All products offered by TopBuy are brand new in their original boxes. They are not used, display models, etc… The savings come from direct imported overseas stock at tax free prices" is this to believe?

Also, in the phones package contents they claim that "(Please note user manual may come as English version hardcopy or softcopy)" shouldn't this always be hardcopy? I've never heard of a softcopy included with the phone.