Snowcap gives you a shorter shasta daisy plant, with all the vigor and bloom of the taller types.
The Shasta Daisies are great plants, hybridized from a European wildflower. They're not invasive like our common daisy, and usually have larger flowers. Whats more, the flowers are classic white, and look great both in more formal perennial displays and in informal wildflower gardens.
In recent years, the hybridizers have worked on this species, creating various flower forms from doubles to all sorts of variations on the original.