There are three main categories of defects as shown in the below figure:Defect Types - Software Testing Interview Questions - Edureka
Wrong: It implies that requirements have been implemented incorrectly. It is a variance from the given specification.
Missing: This is a variance from the specifications, an indication that a specification was not implemented, or a requirement of the customer was not noted properly.
Extra: It is a requirement incorporated into the product that was not given by the end customer. It is always a variance from the specification but may be an attribute desired by the user of the product.