BlockChain is a Linked List?

Yes, blockchain data structure can be viewed as a linked list. Each block within the blockchain references a previous block, known as the parent block in the block header. The sequence of linking each block to its parent creates a chain going back all the way to the first block ever created, known as the genesis block. In fact, this parent block linking is what makes the blockchain immutable.

Parent Hash Linking in Blockchain

However there are certain important differences to note with regards to blockchain.

Blocks are linked using parent hashes and not pointers as in linked list.
Secondly, the data structure in a blockchain is much more complex than a simple linked list. In case of Bitcoin and Ethereum, merkle trees are used for storing the transactional data within a block and then these blocks(essentially merkle trees) are linked via parent hashes.