What is the difference between read-only and PIN-protected notes?

"Read-only" (in the note options menu, Pro) locks a note against edits so a finished document cannot be mangled by accident; it hides nothing. "Protect" (same menu, Pro) hides a note's title and contents behind your PIN or biometric unlock, for the things you would rather not have visible on a screen others sometimes see.

Both are convenience gates on your device, not extra encryption. The flags travel inside the note's encrypted data, and the note is deliberately not re-encrypted with your PIN: that way a forgotten PIN can never destroy data. It also means anyone holding your recovery phrase could sign in on a fresh device, set a new PIN, and read everything. The phrase remains the real security boundary - protect it first, and use these gates for on-screen privacy.