DEMOS comes from ancient Greek, meaning democracy, and also means collective. DEMOS is mainly to provide help for more and more public chains. In the process of helping, they gather public chains.
The main goal of Callisto is to research and develop a reference implementation of a self-sustaining, self-governed, self-funded blockchain ecosystem and development environment. Callisto aims to establish a secure and contribution-friendly environment for further protocol development and improvements. It will rely on a built-in system of smart-contracts to achieve this goal.