This article applies to the deprecated Zotero for Firefox (pre-Zotero 5.0) plugin. It no longer applies to the current versions of Zotero.
The separate link and snapshot buttons were removed from the Zotero toolbar in Zotero 2.0, but equivalent functionality still exists through the use of the Create New Item from Current Page button.
Create New Item from Current Page creates a web page item, which in Zotero 2.0 behaves much like a standalone link attachment but offers significantly more functionality and flexibility.
If “Automatically take snapshots when creating items from web pages” is enabled in the General pane of the Zotero preferences, the Create New Item from Current page button will create a child snapshot under the web page item. Holding down the Shift key while clicking the button will temporarily toggle the setting, allowing you to create a web page item with no snapshot even if the snapshot preference is enabled (or vice versa).
Double-clicking a web page item without a snapshot will take you to the web page, the same way that double-clicking a standalone web link attachment would take you to the web page in Zotero 1.0.
Double-clicking a web page item with a snapshot will display the snapshot instead. You can access the live web page by clicking the “URL:” label to the left of the URL field in Zotero's right pane.