Why do I need to know how to use different browsers? or Why can't I use one browser for everything I want to view on the web?
To answer this question we need to first be comfortable knowing that the internet is a network built on chaos. The world-wide-web is the wild west, a network we cannot marshal. Every website is programmed and designed by different developers using different methods by which they render their design. Often a single website is built from a multitude of programming languages - and there's the rub. Browsers, our windows to the web, are also developed by different programmers who have different priorities. This means that certain browsers may or may not render a website more effectively than another. All browsers accomplish the same fundamental tasks of rendering websites, but some do it better than others. For instance, Firefox has been known to render sites utilizing a lot of Java programming - somehow Firefox rendered Java faster than its competitors. Soon thereafter and a few updates later Chrome and IE accomplished the same tasks just as rapidly. So where does this leave us? Browsers are like wrenches in a toolbox - each does the same basic function, but one size does not fit all. The more we can become familiar with the 3-4 most popular browsers, the better we will be.
Are their major differences between the browsers featured here?
Yes and no. Please refer to the question/answer above. The only major difference is in their manufacturing. IE and Safari are inherent to Microsoft and Apple (the two main software and hardware competitors). Their browsers (IE and Safari respectfully) are not open source, meaning they are proprietary. Firefox and Chrome are derived from open source projects; therefore a community of programmers can contribute programming and features to the browsers.
Which browser should I use for which application?