Eclipse has 3 important bits of terminology which worth wrapping your head around.
A Workspace is the equivalent of a Linux login. In a given Workspace you will be able to access to a given set of Projects. Following on with the Linux login theme, your Workspace contains the colors that you have chosen for your "login", any keybindings you may have and so on.
Eclipse also uses the Workspace to do it's caching. This allows the Workspace to be independent of a given project, and also allows Eclipse to keep the "polution" in your working area to a minimum, storing the intermediate files in the Workspace instead of with your source files.
The location of your Workspace will have a performance impact, please refer to the performance section of the user guide for more details.
A Perspective is a "view of the world". In years gone by, switching between a mode where you are editing code, and debugging your code would require significant re-arranging of windows. Modern IDEs overcome this and other limitations of this model with the introduction of the Perspective. Each Perspective keeps track of the specific windows (Views) you have open, and you can switch between perspectives without having to re-arrange windows.
As HDL designers, we will often have to switch between editing code (SVEditor Perspective) and the perspective that matches the revision control system you are using. When Editing code, your code will dominate the screen. The menu system is also customized to tasks that you would do in this perspective. Take a look at the File>New menu system in the SVEditor Perspective, you will see that the menu system is heavily biased to SVE wizards.
Switching to your revision control system, your source code will probably use less of the screen, with your "History view" occupying a greater chunk of the available screen real-estate.
To open switch perspectives you can use the menu system or the Open Perspective icon shown below:
Window>Perspective>Open Perspective>Other
Eclipse Views are basically windows inside of Eclipse that can be opened and closed. Examples of views include:
Views can be opened at:
Window>Show View>Other