500GB HDD shows 465GB internally

WD External Drives WD Portable Drives
3

The difference has to do with binary arithmetic, not formatting.

See the following Wikipedia articles:
http://en.wikipedia.org/wiki/Gibibyte
http://en.wikipedia.org/wiki/Gigabyte

1GiB = 1024MiB

1MiB = 1024KiB

1KiB =1024B

Therefore …

1GiB = 1024 x 1024 x 1024 = 1 073 741 824 bytes

1GB = 1 000 000 000 bytes

500GB = 465GiB