Reveal as a noun is not used unless you are in the movie business or you are an archietcturer. Revelation can be used in the same way that you would use the word discovery. Example: You and I both were surprised by the revelation that she had secretly married her husband years before she told anyone.

I'd say "to reveal" is when you are revealing something you're showing/telling it for the first time and it is either an object or a solution. In this sense, you can say the revelation of this will happen tonight, but it's a bit forced - better to say I will reveal this tonight. As a noun, I've only really heard it in the context of "the big reveal" - which is a bit of a set expression in itself but means the same as the verb. To have a revelation most commonly means to find an unexpected solution to a difficult problem.