What is the difference between Block and Module? [duplicate]

Possible Duplicate:
What are the use cases for different scoping constructs?

I don't understand the difference between the Matheamtica functions Block and Module. They seem to do the same thing: they both allow the definition of local variables.

• While it may be a duplicate, this is a great way to ask the question that many new users have. – Joel Klein Jan 30 '13 at 20:35
• @JoelKlein I agree. This is why it is best to close this a a dupe, but not delete it, so it will serve as a pointer to the other one. – Leonid Shifrin Jan 30 '13 at 20:36
• @JoelKlein Leonid is correct. A unique way into a problem is often welcome, so likely it won't be deleted. (This improves its searchability, too.) But, it should be closed so effort is not duplicated between the two. – rcollyer Jan 30 '13 at 20:40