Hi, tambaluna.
The answer to your question is that it is neither.
When you create a sidebar (Appearance > Design Settings > Add new Sidebar) you need to give that sidebar a Title and an Alias. The title is so that you can recognise it in the list of sidebars, the alias is what you would use with the [sidebar] shortcode. You may give your sidebars whatever titles you so desire, however it makes sense to make the alias at least similar to the title. For example: “My Little Sidebar” and “my-little-sidebar”.
None of this has anything to do with widgets.
Once you have created a sidebar, if you want to use a widget in that sidebar then you would go to Appearance > Widgets and drag your widget into the appropriate sidebar area over on the right.
N.B. It is always fine to start fresh topics, but if you have questions about something that has been written in an existing topic then it makes senses to continue the discussion in that topic rather than in a fresh one.