What is the difference between Apert syndrome and Crouzon syndrome?

What is the difference between Apert syndrome and Crouzon syndrome?

Apert syndrome and Crouzon syndrome share some of the same characteristics since they both occur when the joints in the skull close too soon during fetal development. While both conditions cause the skull to form a crescent moon or sunken face (midface hypoplasia), the difference between the two conditions is that Apert syndrome also affects body parts beyond the skull, like fused fingers and toes (syndactyly). Crouzon syndrome only affects the formation of the skull.