Windows Server 2016 Storage Spaces Direct, an evolution of Storage Spaces in Server 2012. Both refer to a pool of resilient storage at lower cost than a traditional storage area network (SAN).
The primary use of Storage Spaces was with Scale Out File Server, a server cluster connected to SAS disks in separate enclosures. Storage Services Direct, on the other hand, uses direct-attached disks that can be SAS, Sata or SSDs connected via NVMe (Non-Volatile Memory Express) PCI Express. You can either then connect to a Scale Out File Server over SMB3 (Server Message Block version 3), or use the cluster for both compute and storage by running VMs there directly, a scenario which Microsoft calls Hyper-converged. The advantages are lower cost, more flexibility, higher performance using SSD, and simplified topology.
On the networking side, Server 2016 introduces a new software-defined networking (SDN) stack built on Network Controller, a new server role which also exposes a programmable API. Using tools such as System Centre VMM (Virtual Machine Manager), SCOM (Operations Manager) or PowerShell, you can use Network Controller to manage load balancers, Hyper-V virtual switches and VM networking, firewall rules and virtual Gateways. Server 2016 also introduces support for the VXLAN (Virtual Extensible Local Area Network) standard, alongside the existing NVGRE (Network Virtualisation using Generic Routing Encapsulation). VMMQ (Virtual Machine Multi-Queue) improves network performance for VMs.