So, with Studio they added many "modules" of the whole program. Here's what they are, why they're different, and which one is right for you.

Note: Prices may not be accurate do to adjustments/sales. If a new feature comes out and is not on the list, let me know!

Cost: Free
Good For: Hobby, or just starting out.
The basic edition, very bare-bones in terms of trying to actually publish anything, great if you just want to learn or start out. You can still export your games for other people to use, but they will have a "Made with Game Maker" loading screen and splash screen. Not exactly game breaking, but doesn't look all that professional. It also limits your resources, which is alright for EXTREMELY simple games, makes larger projects a bit difficult. So it's great to start out, and learn the ropes, but if you want to actually do something, I'd plan on buying a higher version. (Frankly, you're better off getting the free version of GM 8.1[www.yoyogames.com])

Cost: $45
Good For: Basic Windows/Mac Development on a budget.
A step up from the basic edition, removes the splash screens and resource limits. This is basically your standard version if you want to work on a free game by yourself, and only want to publish on the desktop. It is full featured, program wise, but it lacks a few of the newer things they added to help make a game more flexible and powerful, as well as some interesting monetization options (in-game ads, ect.)

Cost: $90
Good for: Desktop development, looking to port to other devices. (The "Serious" package)
Basically, this is the full suite for desktop development. If you get really good, and want to start actually publishing games to try to make money, this is the package for you. Includes a lot of extra functionality that makes collaboration easier, as well as makes the engine a bit more flexible. It also has the ability to test builds for mobile, but not publish them. If you make something, and it gets popular enough, you can begin porting it with this edition. They also add a lot of ways to make money in-game, like in game purchases, and advertisements. They are all integrated, so it's much easier to add in.

Now, to the extended export packages:
(Require the professional edition)

Cost: $100
Good for: Facebook/web games.
I also got to try this one out. It is a bit more tricky to port, as a few things are dropped, but it's best to start from the ground up with HTML5 in mind. The main use for this is Facebook games and other web content. It includes Facebook money integration, as well as standard web advertisements. Good if you just want to get a game out to as many people as possible, and there's some chance to get a bit of money back as well.

Cost: $100
Good for: Extreme Multi-Platform
Although this a massive step in the right direction for Linux gaming, unless you own a Linux Device, or really need to be able to export to that platform, I would save this until you absolutely need it or have a well established product, if only because of the relatively (right now) small audience.

Cost: $200
Good for: Android Development. Duh.
I had some time to try out the android export during the beta, and it definitely is worth that $200 if you have a game ready. It is incredibly easy to export, essentially you usually just have to add touch controls. The Android market is also a great place to publish, as there's a lot of exposure, and a very low publishing fee. (Like $15-30 last time I checked, and its one time just to set up a developer account.)

Cost: $200
Essentially the same as the Android Export. Except there's a much higher development fee, and you must own a Mac. Seeing as how quickly android is growing, any increase in exposure dosen't really offset the price.

Cost: $200
Essentially the same as the other mobile exports, but for the Windows Phone 8. I haven't seen any figures on how big this market is, but I would say, as with the Ubuntu Export, it isn't really a "core" platform- unless you simply want to expand past Android or IOS, or specifically need it, the Android (or IOS) module is a better bet. There is also a $99 annual subscription required for the Windows Phone Dev Center.

So there you have it. All the different modules, broken down into somewhat more manageable bits. When in doubt, just get the free version, try it out, and figure out what you need.