Difference Between Bug and Defect

Bug vs Defect

A bug is a deviation from an expected result. It is an informal way of saying a human action leading to an incorrect result. These actions are usually errors or mistakes in either a program’s design or its source code. In the software industry, there is a saying, “All programs have bugs, but the number of these bugs vary with the quality of the program.” A well-written program has fewer bugs, and such errors do not interfere with the normal functioning of the program. A program is said to be buggy if it has a large number of bugs that are seriously interfering with its functionality. A bug can force the program to behave in an unexpected way or perhaps even force it to shut down.

A defect is something that works normally, but it has some features that are not mentioned in the requirement specification document. A defect is identified when a client or user tests the functionality of a product. A defect can lead to irreversible damage leading to the failure of the entire product since it adds features that it wasn’t engineered to do in the first place. Defects usually occur due to poor manufacturing techniques, poor quality control, or using the product in a way it wasn’t intended resulting in the damage.

For most clients, the terms “bug” and “defect” are synonymous. A few are discussed below:
1. Be it bugs or defects, both damage the reputation of the concerned company.
2. A software testing result is sufficient to point out both bugs and defects.
3. A desired level of quality is achieved only when both bugs and defects are identified and this report is
submitted to the developer with requisite feedback.

But there are also a few subtle differences:
1. Defects are easier to describe as they tend to be specific unlike bugs.
2. It is easier to replicate defects as they require a brief explanation.

Summary:
1. A software bug, being nonspecific, refers to an error or an unexpected behavior by a set of computer
programs or code that does not adhere to the requirements.
2. In simple terms, a defect is a mismatch between requirements.
3. Reports of bugs in a program are referred to as bug reports, problem reports (PRs), trouble reports, and
change request (CRs).
4. During module testing, testers identify bugs while users or clients find defects during user acceptance testing.
5. A bug occurs during the manufacturing process whereas a defect gets introduced due to poor quality control
or poor manufacturing techniques.

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