The underlying engine is the same as in Beta, but the product itself is built with different flags, default settings, and other features. For example, add-on si

The underlying engine is the same as in Beta, but the product itself is built with different flags, default settings, and other features. For example, add-on signing is optional in Developer Edition, so it's better suited for developing Firefox add-ons than Beta. Similarly, we may ship new versions of the DevTools into DevEdition before they're ready for the broader Release population.