It's still using Firefox extensions, this is for people switching from Chrome to Firefox (or those who want to use both browsers with the same extensions.) From the article:

"Mozilla decided to create a list of extension pairs for extensions that are available on the Chrome Web Store and the Mozilla Add-ons Store. Instead of importing the Chrome extension directly, Firefox is installing the Firefox version of the extension from Mozilla's own extension store."

So far they have 73 pairs, but should increase overtime and likely cover the most commonly used extensions.

There are extensions that Chrome has, which Firefox does not.