What is the different between line and staff authority?

Here is the wiki def.

Line authority - in which individuals in management positions have the formal power to direct and control immediate subordinates.

Staff authority - granted to staff specialists in their areas of expertise. Narrower than line authority and includes the right to advise, recommend, and counsel in the staff specialists' area of expertise. It is a communication relationship with management. It has an influence that derives indirectly from line authority at a higher level.

and take a human resource manager as an instance

• A HR manager has line authority over the staff of the HR department and staff authority to support , assist , and advise mangers of other Departments in matters related to HR management