Why are downloadable game sizes different between 360 and PS3?

[WiiBox3]

Turkish said:

WiiBox3 said:
The PS3 version is compressed and needs to be installed after downloading. That's why it requires more than double the download size when you download it. After installed, they should be close to the same size.

The xbox versions are not compressed? I heard the xbox just masks the download and install in one.

Possibly. I just know when I download games on the PS3 they don't mask it and for PS1 games they leave the install file on my HDD. But I'm glad they compress it to shorten the download time.