Bug : A bug is a fault in the software that’s detected during testing time. They occur because of some coding error and leads a program to malfunction. They may also lead to a functional issue in the product. These are fatal errors that could block a functionality, results in a crash, or cause performance bottlenecks
Defect : A defect is a variance between expected results and actual results, detected by the developer after the product goes live. The defect is an error found AFTER the application goes into production. In simple terms, it refers to several troubles with the software products, with its external behavior, or with its internal features.
Error : An error is a mistake, misunderstanding, or misconception, on the part of a software developer. The category of developers includes software engineers, programmers, analysts, and testers. For example, a developer may misunderstand a design notation, or a programmer might type a variable name incorrectly – leads to an error. An error normally arises in software, it leads to a change the functionality of the program.
