All blockchain structures fall into three categories:
- Public blockchain architecture
A public blockchain architecture means that the data and access to the system is available to anyone who is willing to participate (e.g. Bitcoin, Ethereum, and Litecoin blockchain systems are public).
- Private blockchain architecture
As opposed to public blockchain architecture, the private system is controlled only by users from a specific organization or authorized users who have an invitation for participation.
- Consortium blockchain architecture
This blockchain structure can consist of a few organizations. In a consortium, procedures are set up and controlled by the preliminary assigned users.
As I mentioned, blockchain is a distributed journal where all parties hold a local copy. However, based on the type of blockchain structure and its context, the system can be more centralized or decentralized. This simply refers to the blockchain architecture design and who controls the ledger.
A private blockchain is considered more centralized since it is controlled by a particular group with increased privacy. On the contrary, a public blockchain is open-ended and thus decentralized.
In a public blockchain, all records are visible to the public and anyone could take part in the agreement process. On the other hand, this is less efficient since it takes a considerable amount of time to accept each new record into the blockchain architecture.
In terms of efficiency, the time for each transaction in a public blockchain is less eco-friendly since it requires a huge amount of computation power compared to private blockchain architecture.