Ornamental gourds are mainly used to provide fall color. They're not the gourds that people have traditionally used in lieu of jugs, pots and the like (i.e., practical functions).
Rather, it is the hard shell gourds that have been used to make everything from birdhouses to dippers. Growing ornamental gourds provides relatively quick satisfaction: I tend to sow the seeds outside in late May and harvest my ornamental gourds in early September. Ornamental gourds are enjoyed immediately, for their fall color; some people save and dry their ornamental gourds, but I myself rarely do.
Growing hard shell gourds, by contrast, is often more of a long-range project. Although I happen to love seeing hard shell gourds grow on their vines all summer long, their most noted benefits start to accrue, for the most part, only after they have been dried. At that point, they can be used as a medium for art work, if you are so inclined, ranging from hats to Halloween jack-o'-lanterns. And depending on the size of the hard shell gourd and the drying conditions, drying can take anywhere from a few weeks to several months.
For this reason, I tend to think of hard shell gourds as being most appropriate for committed gardeners and arts and crafts folks. Casual gardeners will appreciate ornamental gourds as a quick, carefree alternative.