Gian Carlo Menotti's "The Unicorn, the Gorgon and the Manticore" and Carl Orff's "Carmina Burana" have several things in common besides having been paired in a performance at the Kennedy Center Concert Hall Saturday night by the Paul Hill Chorale, with the assistance of The Washington Ballet and the Sidwell Friends Children's Choir.

Menotti called his opus a "madrigal fabie" and Orff termed his a "scenic cantata." Both involve poetry, choral music and dance, and both rely on antique models - ancient mythology and Renaissance madrigals in Menotti's case, and medioval songs and revels in Orff's.

The Chorale came through with most of its colors flying, though Hill had trouble keeping voices and instruments in syne here and there, and the Orff could have done with more tonal pith and rhythmic incision. Baritone Richard Clark was outstanding among the soloists, and the Sidwell Friends youngsters were excellent.

As for the Washington Ballet, making its first Kennedy Center appearance, it has seldom looked better. The performance was as confident and stylish in James CLouser's motley, uneven choreography for the Orff as it was in Heino Heiden's lucid and charming version of The Menotti. Madelyn Berdes, James Canfield and william Miller were splendid in their major parts; other dancers of note included Caroline Lura, Sharon Caplin, Jon Jackson, Richard Mercado, Patricia Berrend, Choo San Gob and Terry Lacy.