Firefox

On desktop I am using Firefox since I can remember. The main reason being the good add-on support and the privacy friendly image of the browser. Although there might be better solution to keep my own data privat, Firefox always felt like the sweet spot between privacy and usability. Now I am using an iPhone and first thing I did, was to install Firefox. But after I learned that all browsers on iOS have to use the WebKit engine, I am wondering what difference it makes to use Firefox there. Is it on iOS more like a skin for Safari, or how much does ist affect the inner workings of the browser? What are the biggest differences?