Jan van den Hemel writes:
Sapling is an add-on that comes with Blender by default, which is used for quickly making trees. The advantage of Sapling is that it is really very easy to make nice looking tree animation, with very intuitive customiseable settings for the wind movement and even for animating the leaves, which makes the whole thing more realistic. Comparing Sapling to Mtree, I'd say that the benefit of Mtree is that you can create a really nice looking tree including preset materials. For realistic animation Sapling has the advantage that it adds nice leaf animation.