Central issues in linguistics and semiotics can be addressed through reflection on the underlying concepts in models and constructs. General models or constructs do not always fit particular instances of their application. General models are useful, but qualitative and ontological differences are given insufficient attention. Some key models and constructs are considered. Qualitative differences in several dimensions are introduced and linked to ontological differences between entities and to the roles, implied capacities of communicators, and to intelligence type. Such qualitative differences must be used to supplement existing classificatory methods and to differentiate the features of communication constructs. They are non-gradient.