Ethereum's goals and build are different in many ways from previous open source blockchains, including Bitcoin.
Ethereum's purpose is not primarily a digital currency payment network. However, the digital currency Ethereum is both essential and necessary for the operation of Ether, which is also seen as a utility currency to pay for the use of the Ether platform.
Unlike Bitcoin, which has a very limited scripting language, Ethereum is designed as a general-purpose programmable blockchain, running a virtual machine capable of executing arbitrary and infinitely complex code. While Bitcoin's scripting language is intentionally limited to simple true/false consumption conditional judgments, Ethereum's language is Turing-complete, meaning that it is the equivalent of a general-purpose computer that can run any computation that a theoretical Turing machine can run.