Tera is a decentralized application platform. This is akin to an operating system. Tera consists of a repository of programs and data storage integrated into the Internet. The mechanism for publishing programs and data on this platform is free from censorship. The circulatory system is the blockchain.
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.