The Edit Offline action is available for every content item. Use this to download a working copy of the item to your computer. This locks the item in the library to prevent others from editing the item simultaneously.
The Inline Edit action is available only for content items created with the Create Content feature in the library. Use this to edit these plain text, HTML, or XML documents directly in the document library.
The Edit Online action is available only for Microsoft Office 2003 or greater files. Use this to edit the content item without first saving it offline.
The Check Out to Google Docs action is available only for items with the aspect Google Docs Editable. Use this to work with items in Google Docs. Like the Edit Offline action, this locks the item in the library while it is being edited.