There are three main categories of blockchain; public chain, permissioned blockchain and the consortium-led Blockchain. As the technology matures, other categories of blockchain may emerge.
Public Chains are open and transparent. Any individual or institution can send a transaction through a Public Chain from anywhere in the world, which is then verified by nodes in the Blockchain. Anyone can compete for bookkeeping rights. The Bitcoin Blockchain is an example of a Public Chain.
The consortium-led Blockchain is semi-public and is usually used within an organization or between members of a consortium. Several nodes are pre-assigned as bookkeepers. The generation of each block is jointly decided by all pre-selected bookkeepers. While other nodes trade and participate in the blockchain, these nodes do not possess bookkeeping rights.
Permissioned Blockchains are completed closed off from the public. Bookkeeping rights are centralized with Blockchain technology used mainly for accounting and the recording of internal transactions. Permissioned Blockchains are used exclusively by a predefined group of institutions or individuals.