Both approaches can play a role in moisture protection, but they solve different parts of the problem.
Interior systems
Interior drainage manages water that reaches the foundation and moves it to a discharge point.
Exterior systems
Exterior treatment seeks to reduce water penetration at the outside wall, often requiring excavation.
Choosing between them
Compare access, foundation conditions, disruption, water source, discharge planning, and total scope rather than assuming one always wins.
What to do before hiring
Photograph the affected area and record when moisture first appears. Ask the person assessing the basement to distinguish water entry from condensation or plumbing, explain what the recommended work will accomplish, and identify the discharge route for any collected water.
If you see significant wall movement, widespread damage, or suspect an electrical hazard, arrange an appropriately qualified assessment before proceeding with routine waterproofing.