What is the difference between Mozilla Firefox and Mozilla Firefox Developer Edition?

Mozilla recently launched a new web browser named Mozilla Firefox Developer Edition, ostensibly designed for web developers.

So I installed it, but I can't find much of a difference between regular Firefox and the developer edition. Every tool which is in the developer edition is already in the regular edition. What does the developer edition provide over the regular edition?

Firefox Developer edition is a modified Firefox that is specifically design for web developers. It also uses a separate profile then regular, running them side-by-side is an option. That does mean that all the add-ons and settings will not be available on F.D.E., but you can use Firefox Sync to get add-ons and settings on both versions.

All features on Firefox Developer edition will be available 12 weeks before they are on regular Firefox.

Some features that are on F.D.E. that regular doesn't have:

• WebIDE:

  allows you to develop, deploy and debug Web apps directly in your browser, or on a Firefox OS device. It lets you create a new Firefox OS app (which is just a web app) from a template, or open up the code of an existing app. From there you can edit the app’s files. It’s one click to run the app in a simulator and one more to debug it with the developer tools. Web IDE - YouTube

• Valence:

  (previously called Firefox Tools Adapter) lets you develop and debug your app across multiple browsers and devices by connecting the Firefox dev tools to other major browser engines. Valence also extends the awesome tools we've built to debug Firefox OS and Firefox for Android to the other major mobile browsers including Chrome on Android and Safari on iOS. So far these tools include our Inspector, Debugger and Console and Style Editor. Valence - YouTube

• Web Audio Editor:

  inspect and interact with Web Audio API in real time to ensure that all audio nodes are connected in the way you expect.

For a more in depth answer, I would refer you to my Q/A on Ask Ubuntu:

• How do I install the Firefox Developer Edition?

Firefox Developer Edition is tailored for web developers. As mentioned here:

By using the Developer Edition, you gain access to tools and platform features at least 12 weeks before they reach the main Firefox release channel.

And also Developer edition includes experimental tools that aren't yet ready to release on stable versions. Basic theme of Developer edition is quicker access to the developer tools.

You can further check here for what's new in developer editor here

As I'm sure you already know, currently, out of the box, it features

WebIDE allows us to develop, deploy and debug web apps. Video
Responsive Design View - see how the website will look in different screen sizes
Valence (Debug any browser) - previous called Firefox Tools Adapter) . Video
Web audio Editor - inspect web audio to ensure all audio nodes are connected as expected.
Page inspector - examine HTML and CSS
Web console - See logged info, interact with web page using javascript
Javascript debugger - debug javascript!
Network monitor - see all network requests the browser makes and how long it takes
Style editor - edit CSS styles

See a general video introduction

Further, it also includes

1. Firefox Hello which is a WebRTC (a tool allowing call and video chat with others from within the browser).
2. Forget button which is similar to clear history.
3. Eyedropper (to 'snap' colours from the webpage)
4. Scratch pad - a stand alone JS console, probably for testing javascript snippets.
5. Connect - connect to a remote device

As you may notice, some (most) of these are already in Firefox or Firefox plugins today... And as time goes on, I suspect will be available in plugins tomorrow. For example, the Page inspector, console, debugger (and a few more) are already in Firebug.

As for changing the screen sizes and CSS, I used a tool called Developer Toolbar...

I have used it as a web developer and designer and it just feels like Firefox with plugins designed to suit a web designer (which is what I think they were aiming for). I'm personally more interested to see how it develops.

At the moment, it feels very similar to the debugger already built into Chrome and IE11 (although I have not played with every feature)

You can also view the FireFox Developer Edition Notes for more detail