:: COMPARE ::
The short answer
Geosmin is one molecule — the main earthy note. Petrichor is the whole smell: geosmin plus plant oils plus a hit of ozone, released together by rain on dry ground.
Side by side
| Aspect | Petrichor | Geosmin |
|---|---|---|
| Is | The full scent | One compound |
| Made of | Oils + geosmin + ozone | Just geosmin |
| Made by | Rain on dry ground | Soil bacteria |
What each one means
Petrichor is the earthy, unmistakable smell of rain landing on dry ground — the scent that rises the moment the first drops hit soil after a dry spell. It's made of plant oils, a compound called geosmin, and a hit of ozone.
Full definition of Petrichor →The contrast above sets out how Geosmin differs from Petrichor on the points that actually matter.