Gigabytes is a term used for very large numbers. Gigabyte is used to refer to anything on the order of GB or 2 to the power of 1024. In gaming we are so used to large graphics that the term gigabyte has almost become meaningless. Here, is why. Gigabytes means you can get a game into a system that will run just fine. In the process it may also increase your system’s memory capacity.
Gigabytes are useful for games like minecraft that have soaps and some other things that can make them too large to fit on a single floppy. If you get your game into the memory, you will be able to expand your system into that many different systems.