Web API is a framework capable of implementing/being RESTful.
Rest isn't a framework its more a methodology for going about implementing your API. There are restful APIs and non-restful API's. You could create a Web API application that isn't restful, its up to you to make it restful.
I suggest you look at this link, or a good search of "Restful Web API" should net you plenty of results.
Build RESTful APIs with ASP.NET Web API | Microsoft Docs[
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