There are different types of blockchains depending on the access rights. Bitcoins was the first blockchain and it is categorized as a public blockchain. This means that all transactions on the network are fully transparent. These blockchains are also called permissionless which means that anybody can participate in the network. Private blockchains are most of the time the exact opposite of public ones. They are often referred as DLT (Distributed Ledger Technology) because of missing properties such as a need for a proper incentive mechanism. Private blockchains can still be transparent but are run by a centralized entity. Consortium blockchains are mostly part of group agreements between companies or institutions allowing only selected nodes to be part of the network.
Read more at BlockchainHub - Types of Blockchains
