difference betwen substantive tests and test of controls.

My answer would be

Test of Controls – these test that the control procedures of the company are being followed and are running efficiently.
eg – ensuring purchase orders, customer sales, etc. are authorized/ approved, ensuring work is signed as being reviewed ( bank reconciliations)

Substantive Test – These test the financial statement for material misstatements at the assertion level.

eg – recomputing figures to ensure accuracy, inspecting assets to confirm that they actually exist and aren’t being made up on the financial statement.