Sculptures that come from ice molds are often not as clear and don't have the clean cuts that carved sculptures do. Some new ice molding methods, however, result in remarkably clear pieces. Often, however, ice sculptures are heavily customized, so it's far more efficient to carve it rather than go to the trouble of making a mold that might be used only once. I've seen ice sculptures on a cruise I was on. Working on a cruise ship is not a prerequisite to be an ice sculptor.
Many people also think that all ice sculptors are chefs.
This is also not the case in part because the art of ice sculpture has evolved to the point that it is difficult for a chef to be a quality chef and a quality ice sculptor. Learning high level ice sculpture techniques is often too time consuming to be a part time effort. However, some of the top ice sculptors in the world are also chefs, and many ice sculptors started learning their art as part of a culinary education. A chainsaw is one of the primary tools of the modern ice sculptor, as are a variety of other power tools and usually specialty chisels. Although these tools can be somewhat dangerous if used improperly, there's always plenty of ice around put on injuries.