We make a lot of different apps, but we do not make a version of Pixlr Editor, our graphic design app, for download on Mac or PC. Pixlr Editor (which some people liken to a free version of Photoshop) is only available on the web here.
We have a breakdown of all of our apps for web, mobile, and online listed here.
Which version am I using?
Pixlr Editor is a graphic design tool that is layers-based. It is a Flash app, it's free, and it has been around for many years in its same incarnation. You will see a screen like this when you open Pixlr Editor:
Pixlr Desktop (Mac/PC) is more about editing photos. It has lots of overlays, borders, and stickers. It also lets you add effects like Stylize (watercolor, pencil, etc.) to your photos. It is more like Pixlr Express on the web. Your screen will look like this when you open an image in Pixlr Desktop:
What you will see if you are signed in as Pro in Pixlr Desktop are the Influence Mask tools. You'll see that on the right-hand side of the screen, like so: