Remember that the auditor is concerned with the risk of material misstatement in the financial statements
Therefore the auditor will assess each of the areas mentioned before (control environment, control procedures etc.) in order to identify risky areas.
The auditor will then undertake tests of control to establish whether the auditor can place reliance on them
Test of Control
These test the systems in place by determining whether the controls over it are sufficient or not
If the control in place is strong, then the auditor is able to place reliance on the information generated by that particular system
These, on the other hand, are procedures to gain direct assurance over a figure in the financial statements.