Blockchain consensus and database replication both help multiple systems stay synchronised, but they solve very different problems and operate in distinct environments.

Blockchain consensus is designed for decentralised and trustless networks. It allows independent participants, who may not trust each other, to agree on the validity and order of transactions. Consensus mechanisms like Proof of Work, Proof of Stake, or Byzantine Fault Tolerant algorithms ensure that once data is confirmed, it becomes extremely difficult to alter. This creates immutability, transparency, and resistance to fraud. Consensus is not just about copying data. It is about deciding which data is valid in the first place, even in the presence of malicious actors.

Database replication, on the other hand, works in trusted and controlled environments. It simply copies data from one database to other to improve availability, performance, or fault tolerance. Replication assumes a central authority or administrator who controls write access and resolves conflicts. If incorrect or malicious data is written to the primary database, it will be replicated as is. There is no built-in mechanism to independently verify transactions.

Another key difference is performance. Database replication is fast and efficient, making it ideal for high-volume enterprise systems. Blockchain consensus is slower and more resource-intensive because security and agreement matter more than speed.

In short, blockchain consensus prioritises trust, security, and integrity across untrusted participants, while database replication prioritises speed, consistency, and reliability within trusted systems.