Communication and connectivity entails being able to access mobile broadband as well as the internet, and connect to other electronic devices like other smartphones, Bluetooth headsets, smartwatches, smart TVs etc.
An ISP also known as an Image Processor (IP), Digital Signal Processor (DSP) or Image Processing Unit (IPU) is a type of specialized microprocessor used for image processing.
Clock speed is only good for comparing the performance of two SoCs in the same family e.g SD665 vs SD660, Helio P60 vs P65, SD865 vs SD865+ etc. The ISA on the other hand tells the extent of a SoC’s abilities and capabilities.