Background: My PhD was in 'Computational Science'. My dissertation was on the analysis of X-Ray Diffraction Data and analysis of thermally perturbed nuclei in the overall dynamic analysis of the molecular electron density for solid state physics. The takeaway? It was very much based in science.
In my opinion Computational Science is the pursuit of science, "... a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe" (wiki), via computational means.
Most position fo 'Data Science', however, seem more like 'data analysis' types of jobs. That is, heavy SQL queries, using pre-built R and Python models (linear regression, etc.) to draw conclusions from structured and unstructured data.
Is Computational Science a superset of Data Science? Are they interchangeable? Is Data Science an actual 'science'? Is Computational Science an actual 'science'?