Lol!!!
Completely INCOMPARABLE. Two different OS's, vastly differing price bracket and best of all, Note 4 will soon be left behind with support (official). Lollipop 5.1? Not exactly the latest and greatest. Ok, the 640xl isn't going to win any beauty contests, or (ridiculous) comparisons to 'flagship' devices.
Let's look at the 640xl in it's proper context. In the UK, you can find one for ?125-150 sterling. Show me a budget android device with a comparable screen size, ram and onboard. Whilst you are looking at the budget android phones, find one that isn't stuck with Jellybean or first release lollipop. Find one with the same camera pixels in that bracket. What about an android that now runs an OS that works, pretty seamlessly with your existing laptop, tablet or PC? How's about the 640xl's little brother, the 640. Buy it in UK for ?49.00. Compare that to a low end droid? There is NO comparison.
Whilst the Note 4 is a very capable device, I've had both 3 and 4, you cannot compare it to a 640xl. The Note is a device aimed at enterprise, the 640 isn't. If you are going to compare the Note 4 with a device, comparable in all areas apart from the screen size, you need to look at the 930. These can be picked up for ?100 on amazon. This device is more comparable on specs than 640xl, apart from screen size.
Maybe we could compare my 5.7" device??
Mmmm octacore, liquid cooled, 3gb ram, 32gb on board, doesn't suffer memory leaks, secure, not open source, amazing screen, can leave my laptop at home and take phone and dock, failing that, WiFi direct etc, OR would that not be considered comparable. I say, each to their own, but if you leave then beat of luck and don't let the door hit you on the butt on the way out