Google Drive's main competitors are Dropbox and Microsoft SkyDrive.  The services are somewhat similar but Google Drive stands apart with its integration with other Google services.  In terms of space, Dropbox offers 2GB free with the option of up with 16GB free when users refer new users.  Skydrive offers 7GB space for free.  Dropbox does not offer a web based editor while Skydrive offers Microsoft Office web apps.