I would start from the definitions of the two, as provided in the PMBOK glossary:
Corrective action: an intentional activity that realigns the performance of the project work with the project management plan. This implies that that a change is needed because something is not working as it should be; i.e., as planned in the PM plan. So you need to take action (a corrective action) to bring the process back to what was planned.
Defect repair: an intentional activity to modify a nonconforming product or product component. Here the focus is on the product or deliverable produced by the project, and a change is needed to correct the error/defect detected.
This seems to be one of my problem area based on my simulator test results.
Can someone help me to learning material on the same, or a set of questions on this to practice
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®