Definition and descriptions of Delay and Deviancy:
In general, a child who exibit progression of development at a slower rate is referred as Delay. Whereas Deviancy refers to anything that is different from normal or expected.
In child language development may include deviant characteristics e.g. echolalia. Many children with autism demonstrate deviance in the development of social and pragmatic skills.
It i a disruption to regular bodily structure and function and symptoms associated with a specific health-related cause.
⇒ WHO (World Health Organisation)