JSFiddle - React, Tailwind, and code Playground
HTML
<img src="https://dl.dropboxusercontent.com/u/42955681/blog/2014-11-30/Spot_the_difference1.png"/>
<img src="https://dl.dropboxusercontent.com/u/42955681/blog/2014-11-30/Spot_the_difference2.png"/>
CSS
img { position: absolute; display: block; top:0; left:0; }
img:hover { mix-blend-mode: difference }