Exception: Carnival has several cabins which are classified as inside cabins but actually have a french glass door which allows light into the room (no balcony, but the door can be opened). Carnival also has some cabins that have a window, but because the window has an obstructed view (that means there is a railing or object in the way) it is listed as an inside cabin. Royal Caribbean has some cabins that have a window but look out over an inside promenade area. These are called "promenade staterooms".
On many ships, basic inside and outside cabins are usually the same size, the difference being that one has a porthole or picture window to let in natural light. Balcony cabins can also be the same size as standard insides and outsides, with the addition of the outdoor space on the verandah; sometimes the interior space is larger. A basic cabin, regardless of category, is referred to as a "standard" unless there is something about it that makes it different (such as physical layout, being handicapped accessible or a designated family cabin). With minisuites on up, you get bigger and bigger indoor and outdoor spaces.
When trying to determine how much cabin you can afford, do not forget to factor in the cost of the rest of your trip. If you have to spend a lot on airfare, pre-cruise hotels and activities in port, you might not be able to afford the fanciest suite; if you are using frequent-flyer miles or do not need to book a hotel, you will have more money for cruise fare; the money you save on airfare can be used to spring for a nice stateroom. Or, look for value-added perks from cruise-line and travel-agent promotions. Offers for complimentary onboard cash, prepaid tips or included airfare can free up some money to pay for other vacation expenses.
Oceanview cabins: These cabins are like inside cabins but usually have a port hole or window. A window is much more desirable than a porthole because the porthole can be difficult to look through. Windows will vary in size and some cabins will even have full floor to ceiling windows. Most window sizes for oceanview cabins are about 4 feet by 3 feet. Be sure to read the cabin description carefully to determine if there is a different type of window. Windows can not be opened. Expect to pay $150 to $250 a night for an oceanview.