Noh and Kyogen
For an American audience, I have wondered how to describe the main difference between Kyogen and Noh theater. To my mind, an analogy would be to liken Noh to formal opera, e.g. Aida or Don Giovanni, and Kyogen to Gilbert and Sullivan light opera, e.g. HMS Pinafore. The object of Kyogen is to make the audience laugh.
Ko-omote is one of the most familiar Noh masks. Usobuki is one of the common Kyogen comedy masks. For anyone interested in further research, a good place to start is with Friedrich Perzynski’s Japanese No Masks from Dover Publications. It includes 300 illustrations of Noh and Kyogen masks.