Windows 7 Features depend on the Windows 7 edition. Microsoft has created the editions so that cheaper editions do not contain as many features as the more expensive ones. The expensive editions on the other hand include all of the features of the cheaper editions. Here is a small chart from least to most complete: (click on a link to be taken to the profile page of the Windows 7 edition.
Wikipedia has created an overview of all Windows 7 features sorted by feature and edition. You can take a look at the table below. A click will open it in full size.