They weight a LOT more. I'd say on average about 3x-4x more. But that's just a rough estimate, it's kind of like asking "how much does a fat person weigh, and how much does a skinny person weigh?" you can only give estimates and averages. The extra weight is primarily water weight in wet mushrooms. When they're dried, you lose that water, making them lighter. ...I guess that's kind of obvious.
