There are a couple of other differences between azaleas and rhododendrons. One difference is in the leaves. Azalea leaves are thinner, softer, and more pointed than rhododendron leaves.
The underside of azalea leaves also have 'hairs' which are long, straight, and parallel to the leaf's surface.
Another difference is on the underside of the leaf. The underside of an azalea leaf, when magnified, is free from 'scales,' or lepidotes, whereas the rhododendron leaves are covered with them.
I lived in Virginia for several years, where the rhododendrons were plentiful. My recollection of them was in their size--their bushes were quite large, and had more greenery visible during the bloom season.
Photos: http://www.azaleas.org/







