You get to wear make-up.
And sometimes cool boots and colorful hats.
There's food and beverages. (Blue beverages, too.)
And you get to hang out with some fun people!
Of course, there are differences. It usually lasts for a couple weeks or even months. And the set does dictate the kind of costume that can be worn. (Although you can always think of it like a themed costume party!)
And not everybody gets to wear a costume. Unless you consider that the crew is dressing up like... a film crew.