Blockchain is a decentralized, distributed ledger technology. It functions as a secure, shared database that records information across a network of computers. Once data is verified, it becomes permanent and unchangeable.

​Cryptocurrency is a digital asset that uses this database as its underlying infrastructure. It relies on cryptographic encryption to secure financial transactions and verify the transfer of tokens without a central bank.
​In short: Blockchain is the foundational technology that enables trustless data storage, while cryptocurrency is simply one popular use case—digital money—that utilizes that security to hold and transfer value.