Zcoin is different from Zcash and uses different cryptographic implementations. It uses the proven cryptographic schemes of the Zerocoin protocol, which was one of the most cited cryptography papers in the past 3 years. Zcash uses the more experimental Zerocash protocol.
A common misconception is that Zcoin is a fork of Zcash. Zcoin is based off the Zerocoin paper while Zcash is based off the Zerocash paper. While the Zerocoin paper and Zerocash paper share common authors and both use zero knowledge proofs, they rely on different cryptography. There is otherwise no relation between the two projects. https://zcoin.io/faq/
