The best way of thinking about this is that you NEVER EVER see a master. You only see "versions". When you import... a version is created, and that is what you see, you do not see the master that is stored away.
When you make an edit, you are making an edit to the version. Then, what you see are changes to that version... but the master (that you never see, is still intact). That edited version will look the same in all of the albums, slideshows, light tables, etc where you are using it.
You can also create new versions from the same master. You can create as many different versions as you choose... and in those cases, each of the versions can look different... ex: color, B/W, cropped, edited, etc. Hence, you can have very different "looks" all originating back to the same "never changed" master.