Here are some of the problems with eggs that I tried to solve: - Cannot be unzipped on top of each other due to the EGG-INFO directory. Wheels repeat the package name in the dist-info directory and are more like their installed layout, hopefully taking all the mystery out of the format. - The egg naming scheme doesn't let you distinguish between Python interpreter implementations (not an important issue at the time). - They include .pyc and so are always [at least somewhat] Python version specific. Wheels don't. - Eggs do not have categories of files. Wheel uses subdirectories of the .data/ directory, and are therefore a complete replacement for most other kinds of bdist_x - And of course wheels use .dist-info which is also something that is newer than eggs, and generally try to bring the useful packaging PEP work into reality. I remember dealing with the zipped eggs hassle, and I remember having to wait too long for binary packages to be uploaded to pypi as eggs when a new Python version was released.