What is the difference between bug and defect?

Showing Answers 1 - 16 of 16 Answers


  • Sep 4th, 2005

Bug: The problem getting at the time of testing. 
Defect: when we get problem on customer's hand is a defect.


  • Nov 17th, 2005


               Bug-which is found before the application goes into production (realese)

               Defect-which is found after the application goes into productio(realese).


  • Dec 16th, 2005

actually a mismatch found by tester during testing is called defect.

this defect when reported to development team and when accepted by developer it is called as bug....


  • Dec 18th, 2005

defect found by testengineer on the build where as bug detected by development team.

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uv nagaraju

  • Dec 28th, 2005

Error: The deviation occurs in Coding is known as Defect.

It is at Developres Level.

Defect: The deviation ocuures in outcome of a System.

It is at Customer/Enduser Level.

Bug: The deviation between Expcted and Actual Result.

It is at Tester Level.


Error leads to Bug and Bug leads to Defect.

If any mistake please excuse.


Jaya guru

  • Feb 9th, 2006

Bug : Error found in the development site before the s/w released to the clientdefect : error found in the client said after the s/w released to the customer

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Kishore Kumar

  • Apr 26th, 2006

Error: Termination in the Application with out any proceedings(Like Show Stopper)Bug: Deviation from the expected result. Effects are not permenant.Defect: Deviation from the expected result. Where the deviation cannot be noted and also the effects remain permanent after the termination of the application.If any error,bug or defect in the above please excuse..............

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  • Aug 8th, 2006


   As per my knowledge

Error is what Leads to defects so when error in code,It leads to defect.

Bug Is when the tester finds the error.And it report that to Developer as Defect.

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  • Aug 25th, 2006

Error: programmatically mistake leads to error.
Bug: Deviation from the expected result.
Defect: Problem in algorithm leads to failure.
Failure: Result of any of the above.

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  • Apr 17th, 2007

Defect: The error detected by the tester during testing is called Defect

Bug: The defect accepted by the developer is called Bug.

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  • May 3rd, 2007

According to me both ara same
In devloper point of view that will be 'BUG'
In Testing team point of view that will be 'DEFECT'


  • Aug 15th, 2007

bug is the discrepancy between the expected value and the actual value.

Defect is in a something that causes the s/w to behave in an incosistent manner with the requirement specification.

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  • Oct 12th, 2007

Bug is a deviation from the requirements
Defect is the deviation from functionality.

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  • May 21st, 2008

Bug : An error (bug) leads to a defect (before release)
Defect : which can cause an observed failure (after release)

Basically it has the same meaning, but depends on the situation 

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  • Jul 18th, 2008

error:  any deviation from specs, any misbehaviour detected at development site is termed as error

defect: when the same is reported by the client/ production site it is termed as a defect, lik we say for any faulty product we use that it is defective same applies for a s/w.

bug: the same termed as a bug in testing terminology.

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  • Dec 1st, 2009

An error is a human action that produces an incorrect result.
A fault is a manifestation of an error in software. Faults are also known bugs or defects.
A fault, if encountered, may cause a failure, which is a deviation of the software from its existing delivery or service.

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A bug related to some wierd behavior of the product which is eventual in the entire life cycle of testing a product at various levels both in dev and test teams. bugs can appear at any stage.

whereas, a defect is surely a problem with the product itself because of its wrong implementation.

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  • Nov 1st, 2011

I disagree with everyone who said there is no difference at all. It is completely wrong!

Error - mistakes in code cause errors.
examples - HTTP 500 internal error, static object error, 404 error page etc
When static object error page is displayed followed by some code, it means that the application/feature has simply crashed.

Bug - Anything that occurs in test/UAT/pre-production environment is called a bug. Another common understanding of bug is deviation from requirements in FRD/FSD.

Defect : Any deviant behavior that exists/discovered in production environment is called a defect. Another definition being: any deviant behavior of the application away from the common expected behavior or anything that cannot be traced back to a requirement is called a defect.

Lets take the example of 'search' feature.

Error: you enter a random text like "4895hfshdga" in search box and you get 404 error page. It means the search functionality either breaks when you enter "4895hfshdga" or it is generally broken. Dev forgot to add or remove part of search feature code.

Bug: Search text box displayed only 19 results per page as opposed to 25. FRD/FSD says 25 results per page must be displayed upon executing search. In this case, bug can be traced to a specific requirement. Let's assume for the sake of simplicity that QA discovered this bug in test environment (before deployed to production).

Defect: If the above bug was found in production and missed in test environment then it becomes a defect. OR
If zero results are displayed for a valid search keyword/string. The requirements doc cannot list all the valid keywords/strings. Sometimes application may be searching meta data.
Please google for "metadata."

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  • Dec 28th, 2011

Bugs and Defects means same but the only difference is who and where it is used.

Bugs are those which is found during a Development phase and which are introduced unintentionally.
Once the product is released to the customers, the bug found by the customers are called Defect. For such defect, customer files defect through Defect Tracking Tool and which in turn solves and release as patches, Service Packs or Hot Fixes.

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Kiran Kumar Thulluri

  • Jan 4th, 2012

Error: Error is a mistake in code

Defect: Due to error in code test engineers are getting mismatches in the application build are defect

Bug: Defects are assigned to developer to be solved
Failure: Not meeting the reliability of the product

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  • Jun 30th, 2013

DEFECT / BUG / ISSUE / INCIDENT: All are same. During the executing time if any functionality is not working as per the requirements we call it as a defect/ bug/ issue/incident.

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