Difference Between Bug and Defect

The process of determining the correctness, completeness, and quality of generated software is known as software testing. It entails identifying flaws in the product that must be addressed before it is delivered to the public. Testing aids in the creation of high-quality software as a final product. A fault or flaw in the software might occur throughout the development process. A defect is a divergence from the original output need, whereas a bug is a programming error.

Bug vs Defect

The main difference between bug and defect is determined by the stage at which they are captured. They are categorized as bugs if they are detected within the testing life cycle. They have deemed defects if they are identified and remedied by the developers themselves, or if they are identified after the program has been produced.

Bug vs Defect

A mistake, defect, or flaw in computer software or hardware system is referred to as a bug. A bug causes a system to act unexpectedly or deliver unexpected outcomes. In a nutshell, it’s any action or outcome that a software or system produces that it was not intended to do.

A defect is a mistake discovered after the application has gone live. It usually refers to a variety of issues with software products, such as their exterior behavior or internal features. In other words, in the context of testing, a Defect is a divergence between predicted and actual outcomes. It’s when a customer’s criteria aren’t met.

Comparison Table Between Bug and Defect

Parameters of ComparisonBugDefect
DefinitionBugs are problems discovered during the testing process.It’s just a difference between what’s expected and what’s occurs in actuality.
Raised byTest engineers.Testers.
TypesLogic, algorithmic, and resource bugs.Critical, major, minor, and trivial.
Reasons for occurringMissing code, incorrect coding, or extra coding.A coding or logic fault and wrong input.
Prevention Operational development methodologies, and assessing the code regularly.Utilizing fundamental and precise software development approaches.

What is Bug?

Bug is essentially a mistake that occurred throughout the software development life cycle. Every problem not only damages the functionality in which it occurs but also has the potential to spread to other parts of the program. When fixing a bug, this ripple effect must be considered. Lack of foresight in predicting such situations might result in major complications and a rise in the number of bugs.

There are several methods for reducing the number of bugs. There are a variety of programming styles and defensive programming techniques that can help in finding issues quickly. Bug-prevention mechanisms are built into programming languages. Restricted namespaces, modular programming, and so on are a few of them.

Furthermore, there are code analysis tools that allow developers to study a program beyond the compiler’s capacity to find a fault. Debugging is the process of repairing bugs. Debuggers are special tools that assist programmers to uncover faults by executing the code line by line. It provides for the observation of program activity by monitoring variable values and other aspects.

In software testing, a bug report is a thorough document that describes the issues that have been discovered in the software program. The bug report includes information such as the bug’s description, the date it was discovered, the tester who discovered it, the developer who corrected it, and so on. Bug reports assist in identifying and avoiding similar issues in the future.

What is Defect?

A defect is an inaccuracy in the system that prevents the planned activity from being carried out. The most crucial job of a tester is to find flaws. Because faults can be detected at any point throughout the software development process, it’s critical to begin testing as soon as feasible. The sooner we recognize problems, the less expensive it will be to correct them.

Testers may come upon such issues when carrying out test cases. Using a defect management approach to handle defects is a good way to go. First, faults are found as much as feasible during the discovery phase. The categorizing phase is the next step. It entails categorizing flaws into high, medium, and low priority categories. As a result, it is easier to determine which flaws should be addressed right away.

Resolution is the third phase. At this point, actions are done to correct the problem. Verification is the fourth phase. It guarantees that the flaws are truly fixed. Closure, the fifth phase, transforms the status of a detect to “closed.” If this is not the case, efforts are made to re-examine the fault. The last process is reporting, which entails disclosing the fault and receiving comments from management.

Main Differences Between Bug and Defect

  1. A bug is caused by a code mistake. The defect is the discrepancy between the actual results and intended outputs, which is discovered in the development environment before the product is sent to the client.
  2. The bug is submitted by the test engineers, and the defect is identified by the testers. In addition, the developer solved it throughout the development period or stage.
  3. Different types of bugs include logic bugs, algorithmic bugs, and resource bugs, whereas different types of defects include critical, major, minor, and trivial based on severity.
  4. Bugs can be caused by missing code, incorrect coding, or extra coding whereas providing inaccurate and erroneous inputs or coding or logic fault impacts the program and causes it to break down or fail, which leads to defects.
  5. Bugs may be avoided by adjusting, advanced, and operational development techniques, as well as routinely evaluating the code whereas Implementing numerous novel programming approaches, using primary and accurate software development methodologies, and using peer review to conduct consistent code reviews to assess its quality and accuracy might help to avoid defects.


In the industry, both bugs and defects must be fixed, and some testing teams use the terms interchangeably. When testers perform the test cases, they may get unexpected results. A Software Defect is a difference in test results. Issues, difficulties, bugs, and occurrences are all terms or aberrations used in different industries to describe defects.

A bug is the outcome of a programming error, whereas a defect is a divergence from the real business need. Defects are issues discovered after a piece of software has been created. Bugs are issues discovered exclusively during the testing lifecycle. Only when both bugs and defects are found and a report is sent to the developer with the necessary comments can the desired level of quality be attained.


  1. https://ieeexplore.ieee.org/abstract/document/6693087/
  2. https://ieeexplore.ieee.org/abstract/document/5645567
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