What are the differences between birch and aspen trees in terms of their physical characteristics and ecological roles?

Birch trees have smooth, white bark and triangular-shaped leaves, while aspen trees have smooth, greenish-gray bark and round leaves with serrated edges. Ecologically, birch trees prefer moist, acidic soils and provide food and habitat for various wildlife species, while aspen trees thrive in a wider range of soil types and support diverse plant and animal communities.