Distortion
Distortion delivers more and denser breakup than overdrive and brings its distortion largely with itself rather than just pushing the amp. That makes a distortion pedal sound more similar across different amps — handy when you want your tone independent of the amp.
Character — More saturated, compressed and aggressive than overdrive, with more sustain and a thicker wall. The line to overdrive is fluid; roughly: overdrive tickles the amp, distortion creates the breakup on its own. The sound carries rhythm riffs as well as singing leads.
Use — Ideal for rock and harder styles when the amp itself stays, or has to stay, clean (small stage, room volume, modeling setup). Because the pedal supplies the distortion, you get high-gain sounds even from a clean combo.
Prominent references — The Boss DS-1 and the ProCo RAT are two of the most influential distortion tones — the RAT with its raw, mid-forward character, the DS-1 as the affordable all-rounder of countless rock records. For denser high-gain walls there's the MXR Distortion+ or modern metal-oriented pedals. Reference points, not a ranking.
Typical controls — Gain/Distortion, Tone (often with more reach than an overdrive's), Level. Some offer a fuller tone stack (bass/mid/treble) to shape the denser sound.
Overdrive, distortion and fuzz are not quality tiers but three tonal colors of distortion — mild and amp-near, dense and self-contained, raw and untamed (next article). Which fits is decided by the music, not the price or the amount of gain.