VMware NSX is one of the most sensational product that VMware produced 5 years back post Niciria acquisition and over the years this product has just gone better and better. NSX revolutionized the SDDC by adding the SDN capabilities and they way how SDN was used before NSX.
One of the major limitation of NSX-V was that it can be used only with vSphere and not with other platforms and customers were continuously demanding for a version of NSX that can be integrated with non-vSphere platforms.
To overcome this challenge, VMware came up with NSX-T which is version of NSX for non-vSphere based infrastructure. This version of NSX can be integrated with other hypervisiors such as KVM and application frameworks such as Redhat Openshift, Docker/Containers and Pivotal. In addition to these platforms, you can integrate your vSphere platform as well with NSX-T.