Motorola Droid 4 is the successor to the Motorola Droid 3. It uses a dual-core TI OMAP processor with both cores having a clock speed of 1.2 GHz. The Droid 3 had a dual-core processor with a speed of 1 GHz. The Droid 4 has 16 GB of internal memory which can be expanded with a microSD card up to 32 GB in size.
CyanogenMod team have created CM 13 ROM for this device. Using this ROM, you can update this device to Android 6.0. Also, you will get better features and performance than the stock ROM. If you are interested, a detailed guide is given below.