
Vanilla extract is an alcoholic flavouring made by steeping cured vanilla beans in a mix of alcohol and water, drawing out their aroma.
ABV 35%+ ABV — but incidental, since it's used only in drops.
A warm, sweet vanilla aroma leads, over a soft woody, resinous note and a faint alcoholic sharpness from the base.
This is an aroma accent, not a sweetener. A drop or two perfumes a drink — an espresso martini, a flip, a hot toddy — without adding real sweetness or body. Because it's concentrated and around 35% alcohol, a larger pour would turn a drink harsh and bitter, not sweet: when you want sweetness and body, reach for vanilla syrup instead.
Only another real-vanilla flavouring will do — the vanilla aroma is the whole point. Imitation essence works but reads more synthetic. If it's sweetness you're after, swap in vanilla syrup and adjust the recipe.
Vanilla essence (imitation vanilla)
Vanilla extract is an alcoholic solution of the actual extractives of cured vanilla beans; vanilla essence is commonly a synthetic-vanillin-based imitation that need not contain any real vanilla and may be alcohol-free.
The extract pulls its flavour from cured vanilla pods soaked in dilute alcohol, and by US law real extract must be at least 35% alcohol and carry a set amount of bean. Its aroma comes mainly from vanillin, the key compound in the bean. The same name is loosely used for imitation "essence" — a mostly synthetic product that needn't contain any real vanilla.