Why are some (all?) files bigger on Mac OS X?

I have noticed this mainly with torrents, but also with other things.

For example, if I download a ~700MB movie, it'll download and take up ~760MB on my mac. The exact same torrent will take up the ~700MB listed on the download page on my Nexus 7, or on a Windows 7 desktop.

I've also seen this space increase with photos from a digital camera (JPG format), movie files from Final Cut Pro, downloaded files like images, word documents, PDFs etc. Mostly with small files the difference is negligible, usually amounting to a few kB. However, when the files are bigger, the difference is harder to ignore.

Does anybody know why this happens? Is it because of the Mac OS X filesystem as opposed to NTFS and FAT on Windows or YAFFS2 and vFAT on Android?

Or does Mac store files in a different way?

I would prefer a canonical answer if possible.

Are you sure that you are always using the same unit ?

Some programs count bytes by multiples of 1000, others by multiples of 1024. This way, a file of one billion bytes will be 1000 000 000 bytes, or 1000 MB (megabyte), but only 954 MiB (mebibyte).

See http://en.wikipedia.org/wiki/Mebibyte

A few years ago, Mac OS X Snow Leopard changed the size of a MB to the standard that mega is 1000000 and not the historical 1048576 [1].

So if you compare the actual number of bytes used by the files, it should be the same.

[1] http://reviews.cnet.com/8301-13727_7-10330509-263.html

It is because

Microsoft defines 1GB as 1024 MB. Apple, on the other hand, defines 1GB as 1000 MB.

See here, here