Google Drive is integrated with and replaces Google Docs. Any file uploaded to Drive can be available for collaboration, and files can be edited directly from Drive. Another perk is that files from Drive can be accessed through an Internet browser on any given computer or mobile device with Internet access. Drive will provide you with 5GB of storage space, which is an increase from the 1GB space in Google Docs.
Drive became available in the UCSC domain over the summer as an opt-in service. If you haven't opted in yet, starting Nov. 8 you will see a banner message from Google in Google Docs encouraging you to switch to the new Drive web interface. Then between Nov. 15 and 29, Google will automatically switch those still using Google Docs to Drive. All your Google Docs will move to Drive, so you won't lose any documents.