Summary of Mozilla products
From MozillaZine Knowledge Base
The Mozilla Suite is the original product from the Mozilla organization (now the Mozilla Foundation). It was designed from the ground up to be robust, standards-compliant and flexible. It comprises a Web browser (usually just called "Mozilla"), an e-mail and newsgroup reader (Messenger), an HTML authoring tool (Composer), a contact manager (Address Book), and an IRC chat client (Chatzilla).
On March 10, 2005, the Mozilla Foundation announced that they would not release any further official versions of the Suite beyond 1.7.x,  since they are now focused on the standalone applications Firefox and Thunderbird. It was agreed that future Mozilla Suite code development would be produced by a group of volunteers, not the Mozilla Foundation. The project was named SeaMonkey, after the longstanding code name for the Mozilla Suite. On January 30, 2006, SeaMonkey 1.0 was released. For additional information see this article.
Firefox is the Mozilla Foundation's standalone Web browser loosely based on the Mozilla Suite's browser component. Firefox is designed to be more flexible and not bound to other applications. Firefox is designed with a different mindset—one to refine the Mozilla user interface and be more user-oriented. It replaced Mozilla as the flagship browser with the release of Firefox 1.0.
Thunderbird is a new standalone e-mail and newsgroup (NNTP) application, based on the mail portion of the Mozilla Suite. Thunderbird is also designed to be a more flexible client, not bound to a single specific Web browser. It became the flagship e-mail client from the Mozilla Foundation with the release of Thunderbird 1.0.
Camino is a Web browser optimized for MacOS X with a Cocoa user interface using Mozilla's underlying technologies. It has many of the features expected in the Mozilla family of browsers, but is designed to make a MacOS X user feel comfortable.
Minimo is a Web browser for mobile or handheld devices such as PDAs. The Minimo project is focused on code-size and runtime footprint reduction, small screen usability, and porting to small consumer devices.
Mozilla Sunbird is a standalone calendar application based on the once-popular Calendar extension for Firefox, Thunderbird and the Mozilla Suite. Sunbird is designed to be a more flexible client, not bound to any other application. The Lightning extension is available for users who need their e-mail and calendar to be integrated. Sunbird and Lightning are still in the early stages of development and only alpha test builds are currently available to the public.
Bugzilla is server software designed to manage software development and track defects. Besides being the system used to track bugs in Mozilla software, Bugzilla is also used by many other companies and organizations.
Gecko is the rendering engine for the Mozilla Foundation’s web browsers, e-mail programs, and other applications which display Web pages. Gecko has a well-deserved reputation for industry-leading support of Web standards, and it also has the flexibility to support the non-standard code often found on the Web. Additionally, Gecko renders the user interface for the Mozilla Suite, Firefox, and Thunderbird using XUL, the XML User-interface Language.