Sorta, sorta not. Looking at the wiki page, it used "EdgeHTML" as the browser engine, which was a fork of ie's engine (MSHTML). But it was a massive overhaul removing a bunch of legacy code and rewriting parts to fit modern standards and to make it compatible with webkit. It was maintained alongside ie11.

I remember testing it out and it being a lot faster than ie was when it first came out, but I've always been a ff user so I didn't switch to it.