Firefox is bigger and has less features.
I might be able to change the "bigger" bit, a bit
Remember I explained Firefox is like a webpage? It's all markup - XUL, JS, CSS, XHTML and some other things. Go to chrome://browser/content/browser.xul and you'll see the browser render the browser.
I'm estimating that there's quite the large fraction of a compressed megabyte that can be saved by removing unnecessary whitespace (there is
alot of it) and comments (particularly the 35-line license blocks that are at the beginning of every second/third source file) from all this markup.
Also, the DOM inspector extension (I don't understand why it's shipped with Firefox atall) comes with
16 locales that I, for one, will never use (
Irish? Who the fuck speaks Irish!?), and I only got the one en-US locale for the core browser stuff - so that's a bit stupid.
BTW, does Opera 8 come with help files like FF, or are they stored online?
Firefox comes with some useless (to the average user) tests in resource:///res/samples
Maybe when FF2 comes out I'll be putting out builds of FF smaller than Opera?