It's pretty simple. The grade dictates the size, facilities and position of each cabin. A large cabin, usually midships on a high deck and with a balcony, thereby affording better views and living conditions, will cost a lot more than a lower deck inside cabin with no natural light. Variations are usually explained, often due to showers being available as opposed to a bath. Hope this helps. Richar.
There are basically 4 different grades of cabin on P&O. Inside, outside (with porthole), balcony and suite. Within each of these grades there are small variations in price due to location on the ship but an inside cabin will be exactly the same whether high up or low down. People prefer midships because it is more stable then at the ends, hence these are more expensive. Strangely though lower deck cabins, which are more stable, are cheaper than the higher decks, but maybe people prefer the view high up. The choice is yours depending on your preferences and the size of your wallet. All other facilities on the ship are available to all regardless of your cabin. You can view the deck layouts and cabin numbers either in the brochure or on the P&O website.
P & O have an extraordinary amount of grades and they are often confusing to the average punter but the main factor remains constant; if by virtue of its' contents, position or situation they can get more money for it then they will, P & O just have managed to take this further than most others.. Nei.
Try reading the brochures! They are very informative and give detailed info. and plans of the various types of cabin . A little bit of study and effort will answer your question far more clearly than we can on here.If still in doubt , invest in a copy of the Berlitz cruise guide.