This is a few years old, but is still a good start.
Novice (levels 1-4)
Level 1:(You have never skied before). You'll learn about your equipment, how to walk and slide with your skis parallel, climb using your ski edges, turn while standing in place, stop and turn using the braking wedge, learn how to get up from a fall, and how to ride a chair lift. Ski on green (easy) slopes.
Level 2: You will learn how to do a gliding left and right wedge turn, ski at slightly faster speeds, improve your balance and stopping skills. Ski on green (easy) slopes.
Level 3: You will start your turns in the gliding wedge, but will end the turn with your skis in a parallel position, if possible with some skidding; ski at faster speeds than in level 2. Ski on steeper parts of green (moderately easy) slopes.
Level 4: You will still start your turns in the gliding wedge, but will have your skis in a parallel position by mid-turn; sideslip exercises; practice skidded parallel turns to a stop (or hockey stop); ski at faster speeds. Ski on steeper green (moderately easy) slopes, adding longer runs.
Intermediate (levels 5-7)
Level 5: You will still start your turns in the gliding wedge, but before mid-turn your feet will be in the parallel position; you will begin using ski-pole touches; experience uneven slopes and easier ungroomed snow conditions; ski at faster speeds and practice on blue slopes; you will begin to see the mountain from a different perspective, and experience the joys of skiing. Ski on steeper green (moderately easy) slopes or blue (intermediate) slopes.
Level 6: You will be in the parallel position throughout each turn, linked with ski-pole touches. You keep your skis parallel on most blue runs if the conditions are good. When the conditions are challenging, you often revert back to a wedge to start your turns. You may experience shallow powder and or small bumps. You should be able to adjust skiing speed when necessary regardless of slope angle or snow type. Ski on blue (intermediate) and sometimes steeper blue slopes.
Level 7: You will develop your skills into powder and bumps and ungroomed snow. Link short-radius turns together. Begin to isolate the skills of turning by pivoting the skis versus turning by tilting them, ski advanced terrain. Ski on blue (intermediate) and easier black (more difficult) slopes.
Advanced (levels 8-9)
Level 8: You apply variations to your turns for effect in varying conditions. Tilting the ski becomes the main tool for turning you instead of twisting the ski with your foot, except in special situations like bumps or quick stops. Explore alternate turn entries-converging, parallel step, diverging, inside ski, one ski. Ski on black (most difficult) and possibly double-black (extreme) slopes.
Level 9: You can ski confidently on any expert terrain and in any snow condition. Ski bumps with short or long-radius turns, ski deep powder, ski steep; use the carved turn as your principal turning method. Ski on all slopes in all conditions.