Coceptionally Bug is same as defect.
But from the point of usage, defect is used by professional and as well as the customers.
Where as Bug is used by professionals only.
Latest Defination of Quality:Quality can also be defined as the presence of requirements or the absence of the defects but also
presence of 'VALUE' in the product.
The Value mentioned in the above passage indicates the user friendliness of that application. The
true value comes from the product if it has functionality as well the usability(user-friendliness).