Druids are pro-Life. Of all the aspects of the world present, they work to maximise the benefits of Life.

However, owing to the Night Elf-centric teachings of Cenarius, that Life almost always takes the form of Forestry, as seen specifically in Desolace, where the creatures native to the area have been clearly displaced by the Cernaion Circle's meddling.

Shamanism has a bit of a wider scope, with the associated lack of finesse. The 3 areas of Shamanism are:

a) the Wild. This includes the Aspect of Life the Druids revere, as well as a cruder version of the animal parts magic shared with Druids.
b) the Ancestors. This is completely absent from the Druids as the Night Elves were immortal, and also bookkeepers, meaning old knowledge was rarely lost. The Tauren, Trolls, and Orcs were never shown to have used much text, prefering oral traditions.
c) the Elements. Capricious creatures generally out for themselves, but have usually reached a nature balance (without outside forces).

Shamans generally tend towards balancing out the above aspects (fairly easy with Ancestors, since they were usually doing the same). But The Elements are frequently at war with the Wilds, and each other.

Shortly, given a natural system which has reached a point of basic equilibrium, a Shaman will leave it alone, unless there is a good reason not to. A Druid will go fiddle to maximise the Life aspect. This fiddling is good/fine in an area with a strong Life component already (like Ashenvale). It is less good in other areas, like Desolace (http://www.wowhead.com/quest=14307 in point), and was particularly catastrophic during Naralex's attempt to clean up the Barrens.