In its first years, the bitcoin system has proven impressive, but it has narrow capabilities. It seemed that we would keep whittling away at its constraints, but the situation changed after the introduction of the Ethereum blockchain, which, unlike bitcoin, can be extended to much more than just managing a digital currency. In fact, Ethereum is a general-purpose blockchain that is more suited to describing business logic, through advanced scripts, also known as smart contracts. As you saw in previous chapters, bitcoin scripts are primarily about expressing ownership conditions and payment rules. For instance, the standard pay to pubkey hash script describes a small program that allows a sender to send coins to a receiver identified by a public key; no wonder, as bitcoin was designed as a cash system. In contrast, Ethereum was designed with a broader vision, as a decentralized or world computer that attempts to marry the power of the blockchain, as a trust machine, with a Turing-complete contract engine. 

Although Ethereum borrows many ideas that were initially introduced by bitcoin, there are many divergences between the two. The following table summarizes the main areas of difference between Ethereum and bitcoin: