Glades are ski runs on which a fair number of trees are left standing, but are usually thinned to allow some space to make turns. They are often also cleared of underbrush and deadfalls (though certainly not completely -- large fallen logs are common features of glades) to keep ski- and board-snagging branches from being hidden under a snow cover of normal depth. Different areas trim and maintain their glades to different degrees--some have very tight glades with lots of "snow snakes" and hidden rocks.
A terrain park is a run that contains man-made features such as half-pipes, single and double jumps, and exposed metal features for sliding along such as pipe or old resort benches. The purpose of a terrain park is to have an area to practice freestyle skiing and boarding, comprised of "tricks" such as flips of all forms, spins, jumps, and the "ducky." Such a run is usually fenced in to keep high-speed skiers and boarders from entering and exiting without slowing or stopping. This keeps them from "hitting" jumps and half-pipes at uncontrolled speeds, or being unable to stop amongst the features or other people waiting to take a turn to do a trick on a certain feature. Depending on the resort, some of the features can be extremely large: jumps of thirty feet or more, half-pipes a hundred or a few hundred feet long, etc.
Chutes are extremely steep, narrow corridors of snow, usually between rock formations of cliffs or boulders. Similar, but generally longer and larger, are couloirs. Couloirs are particularly associated with a high-alpine environment (above timberline), and tend to be avalanche paths. Even in-bounds, some couloirs will have a reasonably stable hanging glacier or cornice above them.
Finally, some areas have permanent snow fields or glacier skiing. Snow fields are present in a certain drainage or on a certain mountain face year-round, and grow and shrink in size with the seasons due to melt and snow deposition, but do not move in the form of snow and ice. Glaciers are defined as having an actual current of snow and ice. This stresses such rigid material as ice, in which large cracks form called "crevasses."
Crevasses can be extremely large, and there is always some danger of encountering them during glacier skiing and travel; however, the danger of falling into a crevasse will be limited (but not eliminated) when skiing in-bounds, as such features will be monitored and marked by the ski patrol of the area in question.