Social Communication and Pragmatic Disorders including children on the autistic spectrum:

Some children with social communication and pragmatic disorders may have relatively good language and speech but not use them appropriately when communicating. For example they may talk about their own interests and not listen to what others are saying; they may interrupt inappropriately and may have poor eye contact when communicating. They will often find it hard to understand the rules behind communicating such as turn taking, responding appropriately to others, staying on topic and using language for a variety of different functions such as  negotiating, informing, questioning, relating, instructing etc

Other children with more severe communication disorders may not have appropriate language or speech and will also not appear to want to communicate. They may be more interested in seeing how objects work rather than tuning in to people and showing an interest in what they are doing or saying. They may also find it hard to make eye contact and follow when someone points something out to them.