Bitcoin Core is the reference implementation most nodes run, maintained by a broad set of contributors. Bitcoin Knots is a Core-compatible alternative, built on top of Core's codebase and maintained separately with a different set of default settings.
Because Knots stays consensus-compatible with Core, it validates blocks by the same rules and won't fork you off the network. The differences show up in policy: things like what transactions your node relays by default, mempool filtering options, and mining-related settings.
For most sovereignty-focused users, the appeal of Knots is having more granular control over what their own node will and won't relay — a policy choice, not a different set of consensus rules.
We can set up either implementation depending on your preference; Knots is simply our default recommendation for clients who want more say over their node's relay policy.