Test Cases or Keywords

Hi all,
I’m new to TA and I’m learning, since I don’t want to start learning in a wrong way I would like to know if any experience tester out there is capable to make me understand the difference between a test case and a keyword.
I’ll explain myself better.
What tells me which is better between creating a Keyword which loops over a list of elements rather than creating a test case which does the same and that can be recalled anytime as well ? Both of them still asks for parameters, so I don’t know when is better to use one rather than the other.
Thank you very much for the attention

A test case is actually a test scenario. It’s basically actions your browser will do on the application.
A keyword is the function behind the scene that does the action on the application. Basically, a test case is a serie of keywords.