Oh, I see what you mean. Right, if we were on BIP-110 rules and switched to Bitcoin Core rules, that would be considered a hard fork. But going from Bitcoin Core to BIP-110 would be a soft fork attempt, although a failed soft fork does behave like a hard fork from the perspective of the soft forkers (although they explicitly updated to it, so there wouldn’t be nodes left behind due to not realizing what happened). I explain it a bit more comprehensively here: https://bitcoin.stackexchange.com/a/30821/5406
Oh, I see what you mean. Right, if we were on BIP-110 rules and switched to Bitcoin Core rules, that would be considered a hard fork. But going from Bitcoin Core to BIP-110 would be a soft fork attempt, although a failed soft fork does behave like a hard fork from the perspective of the soft forkers (although they explicitly updated to it, so there wouldn’t be nodes left behind due to not realizing what happened). I explain it a bit more comprehensively here: https://bitcoin.stackexchange.com/a/30821/5406