The Snapdragon 415 got an affordable octa-core solution which supports LTE Cat 4, 64-bit CPU architecture and 720p display resolution. On Snapdragon 425, it has the X8 LTE Cat 7 modem and expect for a high quality camera shots with enhanced photo processing.
On Snapdragon 620, it has the brand new ARM Cortex-A72 CPUs and next gen Adreno GPU which supports 4K video capture and playback & 2K display resolution. Snapdragon 618 will have the same features but it has the hexa-core variant.
Commercial devices with the 4 newest processors from Qualcomm are expected to be experienced in 2nd half of 2015.