Google Drive allows you to create a special folder (Google Drive folder) on each of your computers for storing the photos, videos, files & documents. Installing the 'Google Drive Desktop Application' on your Mac allows you to instantly sync your photos, videos & files on your hard drive to Google Drive & vice-versa.
Google is still limiting the number of accounts that can access the service during its early days. Google Drive is a cloud storage service by Google which allows you to backup photos, videos & files online to access them anywhere on any smartphone, computer or tablet.