The level 1 project schedule is the very top level of the WBS, which the most breakable tasks, for example, in a website development project, a level 1 project schedule may consist of the following:
All of the above are level 1 tasks,
Level 2 for design will include the following
1.1 - PSD Design
1.2 - HTML Mockup
Level 3 is usually the most granular task (that cannot be broken further), and is assigned to a resource.