Our guess is that the H370 will have 20 PCI-e lanes (versus 24 on Z370) and eight native USB 3.0 ports (versus 10 on Z370), while the B360 will have only 12 PCI-e lanes and six native USB 3.0 ports.
Well, you'd be wrong.
http://hexus.net/tech/news/cpu/108727-intel-coffee-lake-platform-presentation-slides-leaked/
-Integrated Programmable(Open FW SDK) quad-core audio DSP
-Soundwire Digital Audio Interface
-Integrated USB 3.1 Gen 2(10Gb/s or 200 series and Z370 chipset)
-Support for Intel CNVi interface(partial integration of WiFi)
-Integrated SDXC 3.0 controller
It also lists support for next gen Optane Memory and lower platform power state.
"Z370" is a rehashed Z270 with support for Coffeelake, and based on 22nm process. These are next generation,
real, 300-series chipsets on a 14nm process, which is why it allows for feature set additions. Z390, is the successor to Z370, but based on the true 300-series chipsets.
What happened was that Intel needed 6 core mainstream chips for competitive reasons, but 300-series chipsets were months away. If they waited for the chipset, we'd still be waiting for the 8700K. Therefore, Intel decided to modify Z270 to support Coffeelake's increased power requirements. Voila, Z370!