Chord tones can be used to build melodies and keep your playing grounded in what the harmony is. It's a great way to have your solos or melodies make sense and keep the listener's attention. Arpeggios can be used in soloing and makes for a more dramatic and flashier effect without getting to "outside" the harmony that you are soloing over. I have a video posted that covers how to handle a I IV V7 chord progression with chord tones and basically building arpeggios on one string at a time. http://www.youtube.com/watch?v=-orDodMda98
Hope you enjoy!
All the best,