I'm sure this question has come up many times, but I am new to Cake Central. What is the difference between the 2? Are they both applied with alcohol or lemon extract? How different are the effects of the 2? Thank you all for your help !

Luster dust has a shine to it, where petal dust is just a flat color.

You can add alcohol and paint with it (I've had MUCH better luck w/vodka as opposed to lemon juice) or use a dry paintbrush and put on the powder.

Petal Dust is not edible. It should only be used on decorations that are not to be eaten (IE Flowers, hence the name).

Either can be applied dry or wet. Petal dust is generally applied dry to flowers and such for suble details.

I like to use vodka and luster/pearl dust mixed to desired consistancy, the thinner the mixture the lighter the color.

You can apply petal dust dry with a brush then lightly steam the pieces for the color to set, it also adds a little life to the color - boil some water in a pot, wave the pieces for 2 secs over the steam, then set aside to dry.

I use almond extract mixed with either the petal dust or luster dust to paint pieces with since I never have vodka around. You can use any liquid that evaporates dry, don't use water since it'll dry tacky.