Open up these two phones and you'd find the same 3220mAh battery inside. Alright, so it wouldn't be the same one - but it would be the same size.
That means they'll both run for the same amount of time, right? Well probably.
The Nexus 6 has a bigger screen to power, which could count against it, but against that Android Lollipop should be a more efficient OS than the KitKat version on the Note 4. The Samsung phone is loaded with clever power-saving modes, but Lollipop also has one built in. Both also have super-fast charging modes, which can give them a partial re-juicing in minutes. The Note 4's battery is replaceable, unlike the Nexus 6's but how many people really do that anyway?
Once we get full review units in we'll run them both through our arduous battery test, but until then this one looks like a draw.
This one's an easy one: the Nexus 6 will arrive running Android 5.0, or Lollipop, while the Note 4 will be stuck with KitKat for an unspecified time. KitKat's great, but the new OS, as you can see from our guide to the 8 things you need to know about Android Lollipop, promises to be better in so many ways.
Coupled with that there's the fact that the Note 4 will be skinned with Samsung's TouchWiz software. Now TouchWiz was much improved on the Galaxy S5. Plus, it's packed with potentially useful features such as MultiWindow, which lets you run two apps side by side, and handwriting recognition software for the Note's S Pen stylus.
But then again, it's still TouchWiz. Glitchy, packed-with-unnecessary software TouchWiz. Will it be better on the Note 4? Hopefully so. But even if it is, it won't get Google's latest updates anywhere near as quickly as the Nexus does.
Winner: Google Nexus 6
While the Nexus 6 might rule on the software front, the Note 4's the king of features. Come on, it's a Samsung - did you really expect anything different?
Chief among them is the S Pen stylus - improved for the Note 4 with pressure sensitivity and new calligraphy tricks. There's also a fingerprint sensor, as on the Galaxy S5, and a heart-rate sensor (ditto). The Nexus 6 doesn't really have any extra features as such beyond front stereo speakers - the Note 4 has just one on the back.
Still, overall this round's going to the Samsung device.
Winner: Samsung Galaxy Note 4
And the winner is...
Tot up the rounds and you'll get a score of 2-2, with a further three drawn. Which, as you can probably guess, means these two phones are pretty evenly matched.
The Nexus is the better looking phone and also comes running the hugely anticipated Android Lollipop, while matching its Samsung rival in terms of battery, processor and screen. It's also likely to be cheaper. While UK pricing has yet to be announced, the 32GB version costs US$649. The Note 4 will set you back US$700.
Against that, the Note has a higher-specced camera, microSD slot and of course the S Pen and all of its lovely tricks.
In truth, we could go either way, and until we've properly tried out the camera, given both devices a full battery test and seen their screens side by side, we should probably avoid taking sides.
But that would be boring - so we're going with the Nexus 6. Although we reserve the right to change our minds if it proves too damn big to use.
Winner: Google Nexus 6