iTunes is Apple's desktop application for, among other things, managing an iPhone. It also does just about any other media-related job that you might desire. And reasonably well for free software, at that.

iRinger is a ringtone maker, period. It's a desktop application that will convert pretty much any type of sound file (or the sound from several types of video files) to a ringtone for your iPhone. It allows you to clip out the part of the song or whatever that you like, apply various effects like fade in/out to it, and then export it to iTunes. iTunes can then get your new ringtone onto your iPhone.

Clear as mud, right?

What's the main difference between iRinger and iTunes?