Reflective learners prefer to think about it quietly first.
Active learners tend to like group work more than reflective learners, who prefer working alone.
Sitting through lectures without getting to do anything physical but take notes is hard for both learning types, but particularly hard for active learners. Everybody is active sometimes and reflective sometimes. Your preference for one category or the other may be strong, moderate, or mild. A balance of the two is desirable. If you always act before reflecting you can jump into things prematurely and get into trouble, while if you spend too much time reflecting you may never get anything done.