Differences between APIs and Web Services, WCF Service

APIs	Web Services
Although both essentially have the same purpose, not all APIs are web services.	All web services are APIs.
APIs have several types. They support multiple response formats, including XML, JSON, or any other format. Web API’s MediaTypeFormatter formats these responses.	Web Services supports XML.
API is simple to implement and has a lightweight architecture.	Web services need a SOAP protocol to send or receive data over the network, requiring a high-performance architecture.
Any application that supports either JSON or XML can benefit from APIs.	Web services can be used by those applications that use XML for communication.
APIs are versatile with their communication. You can write them in GraphQL, create a RESTful API, or use Web APIs that provide methods instead of calling an endpoint.	Web services can use three types of design styles, i.e., REST, SOAP, and XML-RPC, for communication.
It supports both HTTP and HTTPS protocols.	You can only use it with HTTP protocol.

Feature	WEB API	WCF
Content format	Any media format	SOAP+XML
Service interface	URL Patterns, HTTP methods	Service contracts
State management	Stateless	Stateless with Per Call
Caching mechanism	Built in to HTTP Prefer application control	Handled by application
Error handling	HTTP status codes filters, exceptions	Faults, behaviors
Types	Opt-out	Opt-in