I'm sorry but the OC is correct.. the Mac Pro has been using workstation-class Xeon processors since the switch from IBM to intel. The "Pro" products you refer to are laptops and now more recently the iMac Pros.. There is nothing inherently wrong with your build but it is not in any way a Mac Pro..just a big ass iMac or MacBook Pro with no screen but that can be expanded on. All the major PC manufacturers build their workstations around Xeon processors (which you referred to as "Xeon branded" like intel slapped a sticker on it and charged more..you also failed to discuss the L3 cache of your budget minded i7 which also isn't on the amazon link either..)

Just don't call a donkey a horse, or a horse a unicorn.. You're building a decently capable Hackintosh who's components come nowhere near those of on-market Mac Pros.

I'd like to note that if you had gone with an ATX form factor that you would have expansion options for mainboard/processor combos that would rival if not best current Mac Pros, even if you just started with the consumer level components.