The newest class of Wi-Fi routers use 802.11ac technology, which brings several improvements over previous protocols, including wider channel bandwidth (up to 160Hz compared with 40Hz), more MIMO spatial streams (up to eight), and beamforming, a technology that sends Wi-Fi signals directly to a client rather than broadcasting in all directions.
The 802.11ac protocol also offers downstream Multi User-Multiple Input Multiple Output (MU-MIMO) technology, which is designed to provide bandwidth to multiple devices simultaneously rather than sequentially. That means up to four clients can have their own data stream instead of waiting in turn to receive data from the router. In order for MU-MIMO to work, the router and the client devices must contain MU-MIMO Wi-Fi circuitry.
Comparison of Speed
http://www.trustedreviews.com/opinions/802-11ac-vs-802-11n-what-s-the-difference
http://www.forbes.com/sites/gordonkelly/2014/12/30/802-11ac-vs-802-11n-wifi-whats-the-difference/
http://in.pcmag.com/wireless-networking/40488/guide/the-best-wireless-routers-of-2016