Unlike other task managers, it only shows applications with active tasks.(Those that have potential to consume CPU rather than showing you a list of application residing in memory that might not be necessarily running).
And unlike other task killers or other task managers, it provides info on which application is consuming CPU so you can close them / restart their stats rather than blindly killing them which might in turn consume more battery or break them (Especially Android prior to FROYO).
Here is an excrept from google Android blog on Android app lifecycle management to help you understand this.The fact that you can see an application's process "running" does not mean the application is running or doing anything. It may simply be there because Android needed it at some point, and has decided that it would be best to keep it around in case it needs it again. Likewise, you may leave an application for a little bit and return to it from where you left off, and during that time Android may have needed to get rid of the process for other things.
A key to how Android handles applications in this way is that processes don't shut down cleanly. When the user leaves an application, its process is kept around in the background, allowing it to continue working (for example downloading web pages) if needed, and come immediately to the foreground if the user returns to it. If a device never runs out of memory, then Android will keep all of these processes around, truly leaving all applications "running" all of the time.You can find the full article here: multitasking android way
