While the two solitudes of our title, computerized control and telecommunications, are both concerned with computerized solutions to real world problems, we suggest that they are really addressing different needs and are therefore naturally preoccupied by slightly different concerns. Here we present a taxonomy of key elements intended to make such differences explicit in order to promote more mutual understanding and more collaborative work where concerns are shared. In particular, we suggest that one key difference lies in the nature of the timing requirements associated with reactivity, and whether they are considered as extensions to logical correctness or performance.