A Web Application must have a precise semantics. In currently Web Engineering environments, this can be achieved either by specifying a Web Conceptual Schema, or by using a Semantic Web-language where the Web Application meaning is properly captured. In any case, the set of relevant conceptual primitives has to be properly represented. In this paper both approaches are studied as two different strategies to solve a common problem. The required conceptual primitives are presented, including those data and functional more conventional primitives, and those navigation and presentation more specific of Web Appls.