Corrective vs Preventive Maintenance?

In preventative maintenance we should take proactive measures to ensure a potential problem (or better refer to it as nonconformity) does not occur, while in corrective maintenance we have the nonconformity and we have to locate and document the root cause of it. Moreover, in Preventive maintenance we normally employ system analysis and process to find out how to build in safeguards and changes to prevent nonconformance. In the corrective maintenance, on the other hand,  we take actions appropriate to the severity of the situation by either recalling the product, notifying the customer, downgrading or scrapping product.