OVERDRIVE, distortion and good old dirty fuzz all increase the gain of your signal, but they do so in different ways. All create distortion, so the lines between them can be blurred – the sound of many models genuinely overlaps between the three.
Generally, overdrive is the mildest of the trio and has two primary roles: to boost the gain to drive your valve amp into distortion; and to simulate the sound of a valve amp distorting. Most overdrives use gentle ‘soft clipping’, unlike distortions, which use harsher ‘hard clipping’.
Clipping describes the way in the guitar signal is compressed when it becomes distorted. The harder it is driven, the more the peak of the waveform is flattened (clipped) to resemble a square waveform with increased harmonics and a lower dynamic range.
Overdrive tends to produce a smoother, warmer sound than distortion or fuzz, allowing your amp’s tonal characteristics and your guitar’s tone to shine through more.
This makes overdrive stompboxes ideal for a more organic boost that’s used to push the front end of a valve amp, maintaining note clarity with driven open chords or when you’re breaking into solos.