Children with autism can have habits of personal autonomy very well formed, age-appropriate cognitive level, nevertheless they do not respond to their names, might have delayed speech and language skills, weak or non-existent expressive communication skills, avoids or resist physical contact, routines and resistance to change, and they might resist the performance of any task required by an adult and they might protest vehemently against any attempt to initiate an activity/interaction.
Other children can have major difficulties in staying focused during a task, avoidance of eye contact, problems of personal autonomy, receptive and expressive language disorder, yet to be interested in people around them and in the interaction with these persons.
Autism is often associated with intellectual disability (ID), the latest research in the field reported that many children with autism have an intelligence quotient (IQ) under 60, and only 9 % have an IQ above 85. At intelligence tests, they obtain high scores, most often at performance tasks, and the lowest scores at solving items, which require verbal or social skills. Children with mental disabilities have receptive language disorder, as well difficulties in differentiating instruction, objects, actions.
Attention deficit may occur because the areas of interest of autistic children is limited and, sometimes, much different of what is considered appropriate. Attention deficit is when the child, by overlooking the requested criterion, fails to comply with the mentioned criterion.
They are not attentive to the required details and they solve the tasks according to their own criteria. ''They are not paying attention, but they know'' this is what therapists and parents affirm. The child demonstrates that s/he can solve specific tasks if there exists a strong motivation. Immediately they are offered their favourite reward, they solve the task in order to get the wanted prize.
Almost all children with autism have language impairment, which refers to verbal communication, gestures, or pointing as well. Autistic children don't develop spontaneously non-verbal modalities to express requests, denial, feelings, and so on. Echolalia and autism frequently go hand-in-hand and is, sometimes, the only form of verbal language children with autism can reach. Echolalia may or may not have function of communication and may be immediate or delayed.

Source: http://www.autism-aita.ro/diferente-intre-copiii-cu-autism