I think WCF uses SOAP protocol. WebAPI uses rest architecture. But WCF supports both SOAP and REST.
- What is difference between WCF REST and WebAPI?
- Why is there a general preference for WebAPI?
I think WCF uses SOAP protocol. WebAPI uses rest architecture. But WCF supports both SOAP and REST.
WCF is protocol agnostic. It can run over http, tcpip, net pipes, etc. Web API is more suited for building rest apis.
However, your question is too broad to be answered here. Read more about both technologies and come back with more specific questions.