Earlier quoted context omitted.
The matrix functionality is available in uBlock Origin, no need to install both. Simply enable advanced mode.
The matrix (and its corresponding rules syntax) in uBlock Origin is not as powerful as in uMatrix. In uBO, you can specify how to handle traffic between two origins. You can also choose which type(s) of content can be loaded from a particular origin. However, you cannot specify both at once. For example, you can't create a rule in uBO to allow only image requests from google.com to googleusercontent.com. The uMatrix…
Sure you can:
google.com googleusercontent.com image block
See https://github.com/gorhill/uBlock/wiki/Dynamic-filtering:-ru....The only reason you'd use uMatrix is if you create rules that can't be done with the matrix frequently enough.