Here's a brief overview of the new Socket AM4 chipsets, more info can be found in the slides below.
AMD X300, B300, A300: These are low-end chipsets designed for the most compact small form factor systems. The feature set is extremely limited.
AMD A320: This replaces the current 760G and A68H generations, it's designed for low-end PCs and doesn't have overclocking support.
AMD B350: A chipset for mainstream PCs, it has overclocking support and one of the slides mentions this chipset is much more energy efficient than previous generations.
AMD X370: The chipset for the enthusiast market, it has enhanced overclocking support and two PCIe 3.0 x16 slots.