How is it different exactly? If I had 51% of the hashing power on the bitcoin network, couldn't I change block history and have a majority of the network agree on that new chain?
No. If you had 51%, you could revert one block of history for every 49 blocks of attack time. In addition, you have no ability to create transactions that were not already signed by the owners, nor create bitcoins more than the block reward. This is because of the UTXO model rather than the state machine model. In Bitcoin, every transaction is verified against history, while the EVM chains only verify transactions against state. So if you control EVM state, you can bootstrap every new node to any state you wish, but UTXO verification requires rewriting the entire history.