What's the difference between buying a Mac Pro 2012 (Tower) and upgrading it, and building a "hackintosh" with the same hardware?

Greetings folks!

So my family has a Mac Pro (used for my father's work couple years ago) and it is no longer used. I have already upgraded the hard drive (512SSD + 2TB HDD) and RAM, and I'm planning on getting an Nvidia card for it as well (from http://www.macvidcards.com so it would be compatible).

How does this differ exactly from a "hackintosh"? I mean I would be using unofficial hardware correct? So wouldn't updating the OS to the latest versions keep messing things up? I keep hearing how hackintosh PCs would require lots of maintenance after updating, would replacing the GPU/CPU cause these issues for a Mac Pro as well? because if it will, I think I may be better off building a cheaper PC instead.

Thanks.