From http://www.bikeleague.org/programs/education/courses.php#101: 

Traffic Skills 101 (TS101) gives cyclists the confidence they need to ride safely and legally in traffic or on the trail. Through TS101, students learn how to conduct bicycle safety checks, fix a flat, on-bike skills and crash avoidance techniques. We recommended this class for adults and children above age fourteen. The curriculum is fast-paced, nine-hours, and prepares cyclists for a full understanding of vehicular cycling.

Traffic Skills 201 (TS201) is designed for more advanced students with an understanding of vehicular cycling principles. This twelve-hour course includes fitness and physiology, training for longer rides, advanced mechanics, paceline skills, advanced traffic negotiation, foul weather riding and night riding.

The Group Riding class is for experienced cyclists who would like to go a on a group ride. Students should first be familiar with the techniques for riding predictably, on public roadways, as an individual - such skills as proper lane positioning and emergency bike handling. However, cycling in a group places added responsibilities on each cyclist, so all must understand and practice the principles of group riding. This class is designed to give students the principles of group riding.

The Commuting  class if for adult cyclists who wish to explore the possibility of commuting to work or school by bike. This follow-up class to TS101 covers topics including route selection, bicycle choice, dealing with cargo and clothing, bike parking, lighting, reflection, and foul weather riding.

Bicycling Skills 123  is designed for adults who may not be ready for the full TS101 class. These students need practice with handling drills in order to feel more confident on their bicycle.