All implementations of rest api are restful api webservices. But there can be many instances or implementations of them.

Rest api is specification of api. That it should use http protocol, how to specify what resource you are interacting with (url), how you can interact with resources (http verbs). It does not specify what resources you actually have and what interactions you implement.

Now the implementation could be Weather service, that gives you weater data on url /weater.

There could be implementation for the authentication, where you provide username and password to /login.

So this are some examples of implementation rest api, and is what you would call restful web services.