If you type “about:flags” into the address bar, you can choose to enable or disable the “Experimental Web Platform Features” — which is the EdgeHTML engine:

 

“Automatic” means that some percentage of users are getting the Edge engine, and we’re increasing this over time as we get telemetry that the new engine actually works.

“Enabled” means you get Edge for all Internet sites

“disabled” means you get the IE11 Trident engine.