I have been on the same journey to learn the differnce between Web API (not JUST API) vs Web Services.
First, we know for a fact that both use the Web as the communication tool as stated by @Kris.
While looking at these 2 videos, both serve as the "middleman" (the waiter in the restaurant) for a client to ask a Web Server to process and deliver a response.
When I was looking for an actual differnce between the two, usually most articles and videos go on an unrelated comparison between "Web Services vs API" as they exclude the "Web" out of "Web API".
See this article, for example, which contains the title "Web API Vs Web Service...." yet, contain sub-titles like:
- "Differences of API vs Web Service"
- "Pros and Cons of Web Services vs API Service"
- "Web Service vs API: Fueling Both With Scraping Robot’s API"
The only difference I could find is if we were to discuss this in .NET context.
Here's a question post related to this.
To sum it up, Web Services are used in the SOAP protocal while Web API is usually created in the RESTful way. The more detailed answers are in the post but ultimatelly do not answer the main question that is asked.
Conclusion: The question raised in the public domanin has no clear definition to what is difference between the two, thus the 2 terms are ,for the most part,
interchangeable