Sounds like Windows uncompresses each file, same as done when Windows plays it.
(Lets investigate) Posted by: Reseller Mike "... an image copying piece of software such as CloneCD or Nero or Roxio. Make an exact image of the disc on your hard drive and then copy that image to the blank CD."
If "exact image" does not uncompress then you get same size.
This article is on the compression/decompression algorithms used in digital media.
A codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word codec may be a combination of any of the following: 'compressor-decompressor', 'coder-decoder', or 'compression/decompression algorithm'.