There are many types of phlox flowers, but the most popular kinds are Phlox subulata and the various cultivars of P. paniculata. It's easy to distinguish between these two types, as P. subulata stays short, while P. paniculata is a tall kind. There are other differences between the two (which I'll get to below), but size is a good place to start.
Types of Phlox Flowers
As mentioned above, Phlox subulata is a short plant, and its stature is reflected in its common names: "creeping phlox," "moss phlox," "moss pinks," "ground pink," "ground phlox." Don't let the "pink" label fool you: This perennial does come in other colors. Not surprisingly, Phlox subulata functions primarily as a flowering ground cover, as does ( is the third choice, but it's a little taller). One often sees this spring bloomer blanketing banks with its colorful flowers. Indeed, I list it as one of the top spring flowers.
Types of Tall Phlox
In contrast with its ground-hugging relative (above), Phlox paniculata, or "garden phlox," is sometimes referred to simply as "tall phlox." These perennials are tall enough to be inserted into the middle or back row of a bed of mixed perennials without getting lost. If spring is prime time for Phlox subulata, then the best time for tall phlox to shine is the summer: It's an old standby for the summer garden, a colorful contributor to your yard's beauty long after many other perennials have petered out. As you can imagine, this makes it a valued plant among those looking for a continuous sequence of bloom. Consider investigating some creative landscaping ideas for more on this subject.
'David' is one type of tall phlox; it owns bragging rights in my own landscape as the tallest.
The leaves of Phlox subulata and tall phlox are so different from each other that one would be hard-pressed to identify them as related species in the absence of their flowers. Phlox subulata has needle-like leaves, some of which remain green throughout the winter. The leaves of tall phlox are much larger and die back at the end of the growing season; they are narrow at both ends and flare out in the middle. The leaves of 'Nora Leigh' offer a nice twist in that they are variegated.
The tall phloxes are cold-hardy plants, but they have a tougher time coping with extreme heat. They are susceptible to powdery mildew, which is more difficult to combat the hotter it gets outside. Landscaping enthusiasts who live in hot climates have, consequently, felt cheated when it comes to growing perennial tall phloxes (although Phlox drummondii is an annual wildflower in Texas). But the creators of the "Volcano" series claim that their "Ruby" introduction is the answer for Southern gardeners. Mildew-resistant, one can supposedly grow it successfully as far south as USDA zone 10.