Web Client SDK
The Web API client SDK (WebApiClient) has been replaced by the new Web Client SDK (WebClient) in Sitecore Content Hub 3.0. The old Web API client SDK will be supported until version 3.2 of Sitecore Content Hub so that existing code can be migrated over two major releases.
There are multiple reasons why the new Web SDK was created. Most notably because the version 3.0 introduces Scripting with the Scripting SDK. One major goal was to create a new SDK so that code could be used in both the Web SDK and the Scripting SDK. The new Web SDK also does not work directly with REST API resources anymore. (Almost) everything REST related has been abstracted away, although the Web SDK still features ways to manage HTTP calls.
To get started, here are some important articles:
API reference
The API reference guide provides more information about the classes and the objects used by the Web client SDK.
The examples in these articles use strongly defined return types like IEntity instead of using var which is commonly used in C#. This is done for clarity in the examples, but is not recommended when writing actual code. Using var has multiple benefits.