What is the difference between "Core Services" and "Value added services" in Operations Management ?

Sir according to me core services are services that a co has to provided. Value added service is some thing extra that makes the customer delighted and brings out a Csat survey. 

• In a technical help desk for computers if the nb is not booting up making the computer work would be a core service. 
• Doing something extra like increasing the virtual ram ,deleting the temp files to make the computer faster ,running the necessary updates etc enhancing the performance of the computer would be value added service. 

Core services are basic things that customers want from products they purchase.

Value-added services differentiate the organization from competitors and build relationships that bind customers to the firm in a positive way.

Core Competencies are 1) Difficult for competitors to imitate.

2) They make a substantial contribution to a number of the firms products or services. They give the firm access to several markets.

3) They make a substantial contribution to the perceived customer value of the product or service.

Value added services are Non-Core services, in short, all services beyond standard. This terminology can be used in any service industry.