The indie parity clause dates back to the Xbox 360, where MS mandated that you could not release a game on the 360 at a later date than any other version without having exclusive free content for Xbox owners.
Since the launch of the XB1, MS has revised that policy for the worse. Now that loophole is closed, and devs are not allowed to release an XB1 version of their game, period, if they have already released it on PS4. At the time of the indie parity announcement, MS allowed games that were already announced for PS4 to be released at a later date on XB1. Those games included Contrast, Warframe, and many other PS4 launch window titles. There are now no more titles that fall under this loophole.
There are three ways around this clause. The first is to release your game simultaneously on PS4 and XB1. The second is to launch first on XB1 and release a PS4 version later. Finally, the third is asking Phil Spencer for a free pass, which has NDA'd guidelines and specifics that I cannot get into, nor know the specifics of.