Stealthcoin (XST) has been rebranded to Stealth (XST): https://twitter.com/stealthsend/status/993226001101545473 Stealthcoin provides a complete anonymity solution for cryptocurrencies. Stealthcoin has a fair distribution with nearly four hours of low block rewards, a small premine of 1%, and the long-term energy efficiency of proof-of-stake minting.
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.