Since Samsung is going to launch the Galaxy Note 6 this year, perhaps in August or even earlier, it's understandable that the Korean company would already be testing prototypes. Interestingly though, a report that allegedly comes from a reliable source claims Samsung has created two different Note 6 versions, yet will decide upon one of them before the unveiling, and the other model will not be launched. The Galaxy S6 edge+ from last year will not get a successor in 2016, so basically the Note 6 will serve double duty, both as the follow-up to the Note5 but also the S6 edge+.
Hence it makes total sense that one of the Note 6 prototypes comes with a doubly curved screen, just like the S7 edge and previous edge-branded handsets before it. The second prototype has a flat display, and their other specs are identical.
The Galaxy Note 6 will feature a 5.8-inch QHD Super AMOLED touchscreen (whether curved or not remains to be seen), the same 12 MP dual pixel camera that's in the S7 and S7 edge, 6GB of RAM, and a 4,000 mAh battery. As for the chipset employed, there are once again two to speak of - a new (but unnamed) version of Samsung's own Exynos 8 Octa (with slightly higher clock speeds than the 8890 in the S7), as well as Qualcomm's Snapdragon 823. It's likely that some markets will get the latter, while most will see Samsung's own silicon, emulating what's happened with the Galaxy S7 and S7 edge.
The internal storage will be 32GB, expandable via a microSD card slot. Samsung will apparently make the Note 6 official a very short while after Google launches Android N, and the Note 6 should run that version of the OS from day one. The Note 6 will of course sport a fingerprint sensor, but it may also come with an iris scanner.
Obviously, even if everything you've just read is 100% accurate right now, small changes could still occur before the phablet is outed, so do keep that in mind.