What are the differences between static budgeting and flexible budgeting?

What factors differ the former and the latter.

Static Budget: Shows the expected results of a responsibility center for only one activity level. Once the budget is made, it is not changed, even if the activity level changes.

Flexible Budget: shows the expected results of a responsibility center for several activity levels.
The flexible budget is more accurate than the static budget because budget amounts adjust for changes in activity.