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There may be changes by now, but it sounds like ethereum because at least originally it was literally a direct copy/fork of ethereum.

There are a variety of key differences with the design from Ethereum, it was not a direct copy, changes were made before we ever went live. EXP is much more rare, different block timing, different difficulty algo, no difficulty bomb for mining, no ICO. Of course later, no fork to save DAO funds needed. Borderless is also entirely original code built on Expanse for Decentralized Governance. ETH is much more corporate and EXP is more grass roots, although we do have big business partners and bonuses, like Microsoft Azure, Bizspark+, and Centurylink Cable. :)