Failure -
When a defect reaches the end customer, it is called a failure. It is a deviation of product or software from the expected delivery or services. For Example: If you are driving a car on road,
there is two ways goes:
(a) Left goes to Goa
(b) Right goes to Hyderabad
You have
to go towards Hyderabad it means you have to take turn at the right, but by
mistake you take the left, from that position that is called as
"Error" because human interaction is there and now Fault is there
till you will not reach the Goa, but when you reach Goa that is a final stage
which is called "Failure" because you had to reach Hyderabad but now
you are in Goa.
Defect -
If the defect is detected internally and resolved
it's called a defect.
It is a variance between expected and actual Result. If
Product/ Software is running at client
side on beta version, an issue is caught in that application and it is deviating
the actual result from the requirement or client specifications, that issue will
treat as defect in that product