Spasticity is usually caused by central nervous system injuries, such as brain injuries or spinal cord injuries. Spasticity is a little different from stiffness.
Cerebral palsy refers to a group of conditions that are caused by problems in brain development and that affect how movement and motor control happen in children. Problems with walking and talking are often the way people start a conversation about cerebral palsy.
One of the things that we typically forget when we look at kids who have conditions like CP, is that they're first and foremost, children.