I've only cruised once before and someone else booked it for me.
I'm now trying to book my own cruise - can someone explain what the categories mean.
I notice there are cabins on the same decks but they are different categories, does that have to do with their placement on the ship?
Categories refer to the size of the room. If you go to the website of the ship which you can find at Yahoo Travel among other places, you should be able to pull up a screen that shows you the difference. Remember also that you have many decks in different parts of the ship. All of these effect the category and the price.
There are alot of things which determine the categories. location is one of them. Others include room size, view, inside/outside cabin, which deck the room is on, etc. And each cruise line have their own criteria for each catagory.