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.
Shardus is building distributed ledger software to remedy the problems of traditional blockchains -- scalability, decentralization and efficiency. The technology being developed will use compute and state sharding to accommodate billions of daily active users, allowing for global-scale decentralized networks.