I’m writing this post as lot of people seem to have some misunderstanding how the BCS Client Object Model works. BCS client object model is different from SharePoint Client Object Model. It comes as a part of Office Professional Pro SKU and contains classes which help to consume/update data from External System using Office Clients….
If you are creating and external list via code or CAML and need the type id( the Int32 value for list types) , then the Id for External List is 600. This corresponds to value used by SPListTemplateType Enumerations. For values of all list types, refer: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.splisttemplatetype(office.14).aspx