bug:we will get  bug in testing phase
defect:will get deffect in requirements phase
if it is wrong pls correct

Bug: " before fixing the eror can be called as a bug at low 
intencity and low priority." this will be called by 
developers.


Defect: " can be called by the testers."

The testing team find an mistake that is calld bug.

that bug is accpted by the developer then that bug is 
called defect.  if the developer is not accepting the bug 
then it is not a defect.

If developer will accept the defect it is called as a bug.
Deviation from the requirement is called defect.

defect: if an incompliance with requirement is found in the 
testing phase,by testengineers, it is defect(product is not 
delivered)

bug: if an incompliance with requirement is found in 
maintainence/use, by customer, it is bug(product is 
deliverd to real customers)

acc to me babji it is exactly contrary to what u r saying
Bug is a term used in production side that is by the tester
actually bus is manifestation of error in the s/w
and defect is a term used in non production side i.e by the
customer or user
correct me if i m wrong