There are several ways to tell the difference between rhododendrons and azaleas. Rhododendrons all are evergreen plants while azaleas are either deciduous (sheds leaves annually) or evergreen. You can also tell by the size of the plants: Rhododendrons are much larger than azaleas - both their blooms and leaves are bigger. In addition, azaleas have tubular-shaped flowers while rhododendrons tend to be bell-shaped. And finally, azaleas only have one flower per stem while rhododendron flowers grow in round bunches at the ends of branches.