Difference between Quality and Reliability

Quality is a broader aspect than reliability. It includes the organization, product, people and so on. It shows how well a product performs its intended functions.

Reliability is the possibility that a product or service will provide its intended functions and maintain its level of quality for a specified period of time. Reliability combines all to-gather –

  • Possibility of success
  • Quality for a definite period
  • Durability in specified conditions
  • Availability to perform intended functions
  • Meet the satisfactory level

Difference between quality and reliability



Quality is the degree of excellence that is provided by a product or service

Reliability is the probability that a product can perform defined function without any failure under stated conditions for a stated period of time

It is the snapshot of the beginning of the product life

Motion picture of day to day life

Quality is present that means today

Reliability refers to future

It has much broader aspect

It is the subset of quality

Improving the performance of a system by using a low quality components is impossible

Improving the performance of a system by using a low reliability components is certainly possible

Doesn’t depend on factors

Depends on numerous factors

Static measure of product performance

Dynamic measure of product performance

Quality is observed

Reliability is experienced

It can be controlled and measured to the accuracy

It is just a probability

A customer buy a product on the basis of quality

Customer re-order a product on the basis of reliability

Product quality is measured prior to customer’s initial product use

Product reliability is measured during or after customer’s product use

It shows how well a product performs its intended functions

It shows how well the product maintains its level of quality overtime through various conditions

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