what are the differences between those 2?

Solution
The H110 is not suited for overclocking, it's a smaller micro-ATX board, cannot fit multiple GPUs, also has room for less hard drive SATA ports. The Z170 would have better build quality in particular VRM cooling.

Both of those boards support DDR4 2133Mhz RAM. If you're not overclocking, get the cheaper H110 board.
The H110 is not suited for overclocking, it's a smaller micro-ATX board, cannot fit multiple GPUs, also has room for less hard drive SATA ports. The Z170 would have better build quality in particular VRM cooling.

Both of those boards support DDR4 2133Mhz RAM. If you're not overclocking, get the cheaper H110 board.
 
Solution