Ethereum Classic is most time referred to as Ethereum's old version, the project is a split version of Ethereum. Ethereum Classic came up in 2016 after the fatal incident that happen on the Ethereum smart contract blockchain that resulted in the lost of funds worth millions of dollars. It was developed to retain codes of past transaction history which allowed those who's funds were stolen to be paid back, but being an older version of Ethereum due to the split it suffer from scalability and efficiency in handling transaction and not only that the level of security on Ethereum Classic was very critical, and I won't advise any one to use the blockchain network for financial transaction cause it has a less optimize system instead Ethereum blockchain is a better and more preferable option cause it has been built and made immutable against security lapses and delay in handling transaction process.