The difference has to do with how a computer measures a megabyte and how a hard drive manufacturer measures a megabyte. Computers operate in binary (powers of 2), so a megabyte is 1,024 kilobytes, which is 1,024 bytes. Hard drive manufacturers operate in metric, so one megabyte is 1,000 kilobytes, which is 1,000 bytes. The label of the capacity of the drive is in manufacturer's terms and an approximate measure, so the computer will see it as less.
A trend has started to signify the difference. KB/MB/GB is now sometimes being used for multiples of 1000 (manufacturer's terms), while KiB/MiB/GiB (kibibyte/mibibyte/gibibyte) is being used for multiples of 1,024 (computer terms).
In computing, a custom arose of using the metric prefixes to specify powers of 2. For example, a kilobit is usually 210 = 1024 bits instead of 1000 bits. This practice leads to considerable confusion. In an effort to eliminate this confusion, in 1998 the International Electrotechnical Commission approved new prefixes for the powers of 2. These prefixes are as follows:
kibi- Ki- 2^10 = 1 024
mebi- Mi- 2^20 = 1 048 576
gibi- Gi- 2^30 = 1 073 741 824
tebi- Ti- 2^40 = 1 099 511 627 776
pebi- Pi- 2^50 = 1 125 899 906 842 624
exbi- Ei- 2^60 = 1 152 921 504 606 846 976
The Commission's ruling is that the metric prefixes should be used in computing just as they are used in other fields. Thus, 5 gigabytes (GB) should mean exactly 5 000 000 000 bytes, and 5 gibibytes (GiB) should mean exactly 5 368 709 120 bytes.
The fate of this innovation is uncertain. So far, very few people are using the IEC binary prefixes. Searches for them on the Internet turn up, for the most part, complaints by people who don't want to use them."
My PlayStation2 HDD guide.
NTSC J SCPH 30000 with HDD and PSBBN 0.32
NTSC U/C SCPH 30001R Astral Blue LE PS2
Final Fantasy XI status:
Server - Ragnarok, Race - Mithra, Jobs - BLM 72 WHM 51 SCH 39 SMN 25, Nationality - Windurst, Name - Bungiefan