Is HDR+ on the Pixel the same as HDR+ on the Nexus? No, it's new and evolved!

So, Google's camera app has had this feature, called HDR+, for years now — it's just like HDR, "but better", or at least that's what the name suggests. With the new Pixels, everyone has been raving about how awesome HDR+ is and how you virtually have no reason to ever turn it off. But, since it's the same branding, does that mean that the HDR+ on the Nexus 5X and Nexus 6P is just as good? Are they the same thing? Is the McRib ever coming back for good?

Our answers to those questions would be "The Pixel is better", "yes and no", "probably not, it's a terrible sandwich". ...