What's the difference between planned dates and estimated dates?

Planned dates indicate the scheduled start or finish date of a project or task and form the basis for task planning.

Estimated dates indicate the projected start or finish date for the project, task, or task assignment. When you capture progress for a project, estimated dates equal the planned dates for tasks and the assignment dates for task assignments. You can revise estimated dates for task assignments and lowest-level tasks without assigned resources. You can compare estimated dates from the latest published progress with planned dates and baseline dates from the project plan.