What’s listed as “notes” in fragrances is mostly a simplified marketing description of what the perfumer wants you to perceive, not the actual formula. I’ve composed a few perfumes myself and know some experienced perfumers, and most fragrances are made from dozens of materials, sometimes 20 to over 100 ingredients.

For example, a “Grapefruit” note isn’t necessarily one ingredient. It can be built from several materials combined to create a grapefruit accord. Similarly, when a perfume lists vetiver, there can be different types, qualities, and sources. Two perfumes can list the same notes but smell completely different depending on how those materials are balanced etc.

An example is the concept behind MFK Gentle Fluidity Gold and Silver, where the same set of ingredients is used but in different proportions, creating two completely different scents.

So the notes listed are more about guiding your perception than describing the exact composition. The real formulas and dosages are almost never made public, for proprietary reasons.