I'd argue that the key difference in Firefox was the UI. It was slimmed down and tidied up, with all the unnecessary clutter removed. Firefox also shamelessly

I'd argue that the key difference in Firefox was the UI. It was slimmed down and tidied up, with all the unnecessary clutter removed. Firefox also shamelessly copied and polished up the best features from Opera (i.e. tabs and integrated search), attracting many early adopter Opera users, plus the fact it was free rather than ad-supported gave the browser a wider audience than Opera ever could. Changing the name, the theme and the unused Communicator bloat (Mail, Composer, Chatzilla) was more symbolic in distancing Mozilla from the negative associations of the mostly terrible Communicator than anything else. It's interesting to read the comments from Phoenix 0.2 on Slashdot (http://developers.slashdot.org/story/02/10/07/1739241/Phoenix-02-Web-Browser-Lean-Mean-Mozilla http://developers.slashdot.org/story/02/10/07/1739241/Phoeni...). Their comments system is terrible these days, though.