Mozilla has introduced two new ways for developers to create add-ons for the Firefox browser: a new Add-on SDK and the beta of an Add-on Builder.
The Add-on SDK is set of APIs bundled with a command-line utility that allows you to develop add-ons with your own tool chain. The SDK enables developers to choose their own code editor, access their development files locally and gain greater control over SDK build steps. The Add-on Builder is a Web-based development environment that provides additional functionality for working with the Add-on SDK. The Add-on Builder enables developers to edit code in a feature-rich environment, test their add-ons instantly, and use built-in version control and sharing.
In short, Horner said the Add-on Builder Beta is a hosted, online build environment, and provides a robust code editor with built-in revisioning, module selection, testing tools and build tools. And the SDK is downloadable for developers who are comfortable with a command-line interface and prefer to use their own development environment.