Perhaps the least well understood of the numerous Windows Vista user interface types, Windows Vista Standard is only available on Windows Vista Home Basic (and Home Basic N), and only on systems with compatible graphics display hardware. What's odd about this situation is that the underlying graphics hardware must be capable of running the vaunted Windowsuser interface; but because the low-end Vista Home Basic product edition does not include that feature, Microsoft has created a special UI that looks somewhat like Aero and offers some of the same display techniques.
Confused? Think of it this way: Windows Vista Standard looks a lot like Aero, but drops many of the effects that make Aero special, and utilizes a combination of Windows XP-era graphics technologies and the desktop composition technology Microsoft invented for Aero. What you lose, visually, is the window, taskbar, and Start Menu translucency and transparency effects from Aero, as well as special Aero features like Flip 3D and Live Taskbar Thumbnails and smooth windows animations.
Still, Windows Vista Standard is pretty attractive, especially if you prefer the opaque look of its windows. And you still get some of the little visual cues that most people associate with Windows Aero, including the "light up" window buttons and the irregularly-shaped Start Menu.
Generally speaking, Windows Vista Standard should be enabled by default on any Windows Vista Home Basic system with Aero-class graphics hardware. On such a system, you'll find that the Window Color and Appearance control panel looks almost identical to that of an Aero-based system: All that's missing is the "Enable transparency" option.
When you click the "open classic appearance properties for more options" link, you'll see choices for Windows Vista Standard and Windows Vista Basic at the top, instead of Windows Aero and Windows Vista Basic, as with most Vista-based installs. All of the same effects---ClearType, menu shadows, and full window dragging--are available in Windows Vista Standard as in Windows Aero.
From a technological perspective, Windows Vista Standard utilizes the desktop composition technologies from Windows Aero and requires a compatible WDDM (Windows Device Driver Model) driver. Thus, Windows Vista Standard is more reliable than Windows Vista Basic and doesn't suffer from the the same performance issues as that low-end UI. It's also a heck of a lot more attractive than Windows Vista Basic, so it's a nice option for those stuck using Windows Vista Home Basic.
Fun fact: Windows Vista Standard was codenamed "Aero Express" during the Windows Vista beta.
Tip: If you enjoy the opaque windows seen in Windows Vista Standard, you can get the same effect with Windows Aero, even though you won't see an option for Windows Vista Standard in Display Properties. To do so, open the Window Color and Appearance control panel and un-check the "Enable transparency" option.
Tip: Don't confuse Windows Vista Standard with the Windows Standard display scheme; the latter is simply a Windows Classic color scheme that will cause the system to somewhat resemble Windows 2000. It is based on older display technologies that were present in Windows versions before Windows XP.