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There are many managers confused about the difference between WBS and project schedule, so they schedule as they breakdown project structure in one step. Please highlight the difference and the importance of separating the two steps for successful project.
When it has been asked from planner/scheduler to develop schedule, then planner/scheduler first develop the WBS based on the scope and cost which is agreed by all. Once it is agreed then planner start adding more activities /details or steps to complete below the WBS . The overall WBS and detail activities/step to complete the project is as per time is called proejct schedule.
Project schedule is the WBS ordered as a timely events.
The WBS will give you information about what "tasks" should be done, schedule will answer your questions like when the task should start, what time it takes to complete,tasks predecessors& dependencies, over all execution time, milestones, and other events ..etc
A Work Breakdown Structure (WBS) is a hierarchical decomposition of a project into manageable chunks. It is graphical and shows all the project parts in an organised chart. Unlike a Gantt chart, it does not show the tasks organised in sequence over time. WBS is used at the start of a project to define the scope, estimate costs, allocate resources, manage risk and create schedules. A good WBS looks like an Organisation chart or Tree diagram, with all parts connected and no redundancy.A Gantt chart is created from the Work Breakdown Structure and is a bar chart that tracks tasks across time. It shows the start and finish date of each task and their relationship to each other. A tracking Gantt chart can be used to show progress over time, using a percentage completed for each task and whether ahead or behind against today's date. A Gantt chart also shows the Critical Path; the longest duration path through the schedule. If a task on the Critical Path is delayed by one day, the entire project will be delayed by one day.
WBS comes first, plan comes later. When planning process for a project begins, the SOW is compartmentalized in manageable parts (variable from project to project). Those parts are nothing but WBS. Once the WBS is in place, it is entered in a project plan/ schedule to assign time and resources.
They might be identical in some projects excluding the time frame that must be present for the schedule.
When it has been asked from planner/scheduler to develop schedule, then planner/scheduler first develop the WBS based on the scope and cost which is agreed by all.
WBS is output of create WBS process in scope knowledge area. Project schedule is output of develop schedule in time knowledge area. WBS is created before project schedule. WBS is a heirarchy of what to deliver but it does not tell us how to deliver the delivery. project schedule (time frame to delivery the product) it has time duration, start date and end date of activity, resources necessary, milestone. Project schedule execution results is (SV, CPI) is a base for evaluation the project progress. While WBS can be used to copare end results project with what was planned.
The difference is WBS developed under Scope Management processes while Project Schedule generated in Project Time Management Process. For every the same field of project, like we say, Solar project, WBS is mostlikely the same even with different sizes but the Project Schedule depends on the man-hour required when does the project last, meaning to say depends on the size of the project.
