The expressiveness of communication primitives has been explored in a common framework based on the pi-calculus by considering four features: synchronism, arity, communication medium, and pattern-matching. These all assume asymmetric communication between input and output primitives, however some calculi consider more symmetric approaches to communication such as fusion calculus and Concurrent Pattern Calculus. Symmetry can be considered either as supporting exchange of information between an action and co-action, or as unification of actions. By means of possibility/impossibility of encodings, this paper shows that the exchange approach is related to, or more expressive than, many previously considered languages. Meanwhile, the unification approach is more expressive than some, but mostly unrelated to, other languages.