Guitar Effects: Distortion
Distortion and overdrive effects mimic the tone and sound of a cranked tube amp. This is done by boosting the guitar's signal causing the sound to "clip". This clipping is what creates the overdrive or distortion sound.
Overdrive effects produce a more subtle tube amp tone, saturated with less "bite" than distortion.
Distortion effects use higher gain and produce heavier, crunchier tones.