Why the .BIN format over the .ISO format?

[tlogank]

Just a curious question, and I have a feeling there is a good explanation, but I would like to know it......

But how come whenever you download the CD-Images off Sharelive.com and other P2P client hash sites, the format is always with a .Bin extension?
Because I have noticed that whenever I download them, I convert them with WinISO over from a .BIN to a .ISO and it shaves almost 100MB's off most images. and that's a good few hours difference downloading a 679MB file over a 779MB file. They always work when I convert the images over, so I am just confused on why these sites and others would rather use a larger file format, especially when you downloading an image even though it works that same as another, only smaller?
If someone could just give me a logical explanation for this, that would be great.

Thanks!

[Andy_TRN]

Because they use a program to mess around with .bin files like adding a crack removing protections. Which can't be done that easily with .iso. Also the parameters to add a file to a .bin file are very easy (when using linux).

[nasrules]

Good question. And good answer! Thanks Andy!