The specs of both device are clear, but i want to talk a little about both device. Probably After reading this article you can boldly walk in to any Infinix Store Nearest to you and make a purchase.
Top 4 Differences Between New Infinix Note 4 And Infinix Note 3.
1. OS - There are some changes in their operating system. The Infinix Note 4 runs on XOS + 2.2 based on Android 7 Nougat while Infinix Note 3 runs on XOS (an Infinix exclusive custom user interface) based on Android 6.0 marshmallow.
2. BATTERY - In the battery aspect, the Infinix Note 3 carries 4500mAh battery capacity while the Infinix Note 4 is powered by 4300mAh battery capacity. It's obvious that Infinix Note 3 has the highest battery capacity and not only that, is the highest capacity of all Infinix devices.
3. LIQUID COOLING - Infinix also added liquid cooling feature to the Note 4 but is not entirely new, because other big brand like Samsung have been using the liquid cooling feature. You also note that liquid cooling is not a visual liquid but a heat pipe that simply removes the residual heat.
4. CAMERA - In terms of camera, the Infinix Note 4 comes with 13MP back camera, auto-focus, Dual LED flash and 8MP selfie camera while the Infinix Note 3 comes with 13MP back camera, auto-focus, Dual LED flash and 5MP front-facing camera with soft flash.
From the differences above, you can now without any form of confusion choose the phone of your choice.

