What is the difference between weeping willow and willow tree?

Java

a Willow is a whole category of plants in the genus salix, with about 400 different species.

The Weeping Willow is a hybrid between the Peking Willow (salix babylonica) and the White Willow (salix Alba). It is a large deciduous tree with thin branches that hang down, sweeping the ground and swaying loosely in the breeze. They can be found under several species names: salix Alba, salix babylonica, salix x sepulcralis, salix x pendulina. Here's a picture: http://garden.lovetoknow.com/wiki/images/Garden/8/8bWeeping-willow-i.jpg

(source:istockphoto via garden.lovetoknow.com)

A Willow tree is any tree in the genus salix, including the Weeping Willow. But not all Willow plants are trees. Some are more shrubby than tree-like. One very cool Willow tree is the Curly Willow (salix matsudana). Here's a great site that shows a what a young Curly Willow and its branches look like: http://www.robsplants.com/plants/SalixMatsu.php

(source: www.robsplants.com)

There are also many other species of Willow that you can find at:

www.davesgarden.com

www.jprwillow.co.UK/willow-varieties.htm

http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Salix+sp.

http://plants.usda.gov/Java/profile?symbol=SALIX