What Is the Difference between a Soft Fork and a Hard Fork in the Context of Changing a Mining Algorithm?

A soft fork is a backward-compatible change to the protocol, meaning non-upgraded nodes will still recognize the new blocks as valid, though they may not fully understand the new rules. A hard fork is a non-backward-compatible change, requiring all nodes to upgrade to the new software.

Changing a mining algorithm typically requires a hard fork, as the fundamental validation logic is altered, causing the chain to permanently split into two separate blockchains.