What is the difference between apex callout and web services in Salesforce?

hi Anurag,

An Apex callout enables you to tightly integrate your Apex code with an external service. The callout makes a call to an external web service or sends an HTTP request from Apex code, and then receives the response.
Apex callouts come in two flavors.

• Web service callouts to SOAP web services use XML, and typically require a WSDL document for code generation.
• HTTP callouts to services typically use REST with JSON.