The only thing I can find in my pantry says:
Containing no sugar or alcohol, it is designed for those who seek a rich vanilla flavoring in dry form and without the alcohol found in vanilla extract.
In vanilla powder, the flavoring compounds of the vanilla bean are extracted and mixed with a dry base. Vanilla powder is especially useful in a dough or batter that is to be refrigerated as well as in dry mixes for cakes, cookies beverages etc. as its flavor doesn't evaporates as readily as vanilla extract which makes it useful in baking.
To substitute for liquid vanilla extract, use an equal amount of vanilla powder.