The company described the new product as "an evolution of its phone based predecessor, with some added enhancements that take advantage of a tablet’s larger screen size," in a blog post.
From what we can see (which is admittedly not much at this point), that seems to be a pretty good description. The tablet version has room for more UI elements, such as a row of tabs, unlike Firefox for mobile. A tab menu appears on the left side of the screen in landscape mode or on the top of the screen in portrait mode.
Theme-wise, the browser heavily borrows from Honeycomb, Android's operating system for tablets. But you'll still find familiar Firefox elements, including a big back button and Firefox's signature "Awesomebar" -- a URL field that also searches bookmarks, history and synched desktop activity.
Mozilla has still not announced a release date.