Tree Menu represents menu items in clear tree-like hierarchy, which is very appropriate for indexing menu. By default all submenu items are collapsed until you select the parent menu item.
To setup Tree Menu you just need to configure module parameter “Menu Class Suffix” appropriately and the menu system will take care of the rest.
Tree Menu can present menu items with icons and descriptive text, pretty much like Main Menu.
To setup icons you need to configure menu items appropriately just like Main Menu. There are very detailed instructions in template documentation.
Main Menu is very powerful menu built with clean accessible XHTML code structure and effective drop-down submenu panels.
You can add descriptive text to menu items to make them much clearer.
To set up descriptive text, you need to go to menu item settings and add descriptive text to menu item's parameter Link Title Attribute.