The built-in Mac OS X ‘Grab’ software is basic screen grabbing software that ships with the ability to grab individual windows, selections or the whole screen, most screen-capture utilities ship with only basic grabbing options. However, it’s still limited and doesn’t suit the requirements of advanced users. If you need to mockup a desktop interface, for example, you’d have to do a lot of manual work with Grab to make this a realistic prospect.
Layers is an advanced screen-capturing tool that enables you to capture anything that is visible on-screen from your desktop wallpaper to menu icons, all as a Photoshop PSD file. This key difference with this application is that it’s possible to customise your grab by saving one layer per application window (ie. all the open applications you have open on your desktop). By doing this Layers enables you to open grabs in a PSD editor and accurately select the grab you need, quickly and easily.
The application also ships with the usual screen-grabbing options that ship with other tools but its real strength is the ability to put each window icon or object on its own layer. The application is more suited to those who use similar tools on a regular basis but may be confusing for the more casual user.