An animated example of what happens when people with different permissions click a file name.
You just saw how the menu for the file is different for people in different groups. But what happens when people simply click the file name without accessing the menu?
Depending on the SharePoint groups people belong to, they'll get different results. Some people can edit the file, some can open the file in Excel as read-only, and for others, the file opens in Excel Services.
Click the word Play above this picture to see what happens. Take special notice of what happens for the Viewers group.
When Owners and Members click the file name, they get the option to edit the file in Excel.
When Visitors click the file name, it opens as read-only in Excel, but they cannot edit the file.
When Viewers click the file name, it opens in Excel Services where they can see it in their Web browsers.