
Vanilla sugar is granulated sugar flavored with vanilla, from beans or extract.
Vanilla and sugar together, and separating them is easy — plain sugar with a drop of extract rebuilds it. What actually decides the choice is not flavor but the temperature of the drink.
Vanillin sugar
Synthetic vanillin is one note where real vanilla has several. In a hot or creamy drink the difference all but disappears; in a clear cocktail the vanilla reads flat and faintly chemical.
Vanilla syrup
The dissolved version. In a cold drink it is the practical choice, since granulated sugar of any kind stays granulated.
Sealed and dry it keeps for years, since the sugar preserves the vanilla and not the other way round. Damp is the only real enemy: it cakes.