Both effects make the signal dirty by clipping it, so the names can overlap. The useful difference is how much of the original dynamics and note shape remain.
Overdrive often feels like a pushed amplifier. Distortion usually changes the signal more dramatically and keeps the amount of dirt more consistent. Both effects clip the signal, but the usual difference is degree and behaviour rather than a strict technical border. Overdrive often reacts more to picking strength and guitar volume, while distortion tends to create a denser, more consistent level of clipping.
Amount of clipping
Overdrive normally uses gentler clipping. Distortion clips more strongly and produces more upper harmonics.
Dynamics
Overdrive often cleans up when you pick softly or lower guitar volume. Distortion usually stays saturated.
Compression
Distortion evens out loud and soft notes more strongly, which increases sustain but can reduce touch sensitivity.
Typical uses
Overdrive suits edge-of-breakup, blues and boosts. Distortion suits heavier rock, punk and metal rhythm or lead tones.
There is overlap between pedal names
Manufacturers use the words creatively, and a high-gain overdrive can be more aggressive than a mild distortion. Judge the range, compression and frequency balance of the actual device rather than relying only on the label.
Their role in a rig can differ
An overdrive is often used to push an already driven amplifier, tightening the bass and adding midrange. A distortion pedal may provide most of the clipping into a cleaner platform.
Hear what the controls change
- Use a simple riff with both open and palm-muted notes.
- Keep the amp and cabinet settings unchanged.
- Match the output volumes and compare both effects at low, medium and high gain.
- Choose based on the feel and musical job, not the label.
- Lower the guitar volume and listen to which effect cleans up more naturally.
When the effect does not sound right
You judge only by loudness
Match output levels before comparing. A 2 dB increase can seem more exciting even if the tone is worse.
Both sound muddy
Reduce gain and low frequencies. Heavy clipping creates extra harmonics and does not need as much bass as a clean tone.
The louder pedal always wins the comparison
Reduce the level of the louder effect until both sound equally strong. Human hearing usually interprets a small volume increase as more detail and excitement.