Catalog › gamma-Nonalactone + Vanillin
These two appear together in 6 of the accords published to the PerfuMate community. That is a record of two materials used together in real formulations, and it is only that: a record of use, not a recommendation engine. The accords are listed below so the evidence can be read.
Both are filed under Gourmand, Sweet. They share no sub-category: the overlap stops at family level.
Each accord is a formula published to the PerfuMate community, and these are PerfuMate's own reference accords rather than third-party work. The figures are each material's share of the concentrate in that accord.