The EVE Client can download new or changed resources such as textures, sounds, ship models etc. on the fly as they are encountered in game. This keeps the installation files and patches for the EVE Client smaller, allowing quicker access to the game after installing or updating the EVE Client. Those resources are being downloaded into a shared cache folder which can be used by all EVE clients running on the same computer, saving disk space and bandwidth usage in multi-client scenarios.
The installer only contains the basics that are needed to start the launcher, the launcher installs the basics needed to run the clients allowing you to start playing EVE much quicker than it would otherwise. While playing, the EVE client downloads any additional resources into the shared cache as they are encountered.
The Shared Cache
The Shared Cache is the folder where the EVE Clients save all resources to, in order to be reused as needed. By default, the shared cache folder is created within the EVE installation folder. The location of the Shared Cache can be verified and changed through the Shared Cache Settings of the EVE Launcher Settings if on Windows. The location of the shared cache folder cannot be changed on a Mac.
Installing the full client
The EVE Launcher contains the "Download the full EVE game client" setting, which will download all the remaining resource files in order to complete the resource cache. This will limit the resource downloads of the client to changed resources only. Please keep in mind that enabling this option will cause the EVE Launcher to not enable the "Play" button until the download of the additional resources has been completed.