Permissioned Blockchain and Permissionless Blockchain are two different types of blockchain networks that differ in terms of access control and participation.

1.Permissioned Blockchain: In a permissioned blockchain, also known as a private blockchain, access to the blockchain network and participation in the consensus process is restricted to a pre-defined group of participants. These participants are typically known and trusted entities, such as organizations or individuals with specific roles or permissions. Permissioned blockchains are characterized by:

Access Control: Permissioned blockchains have a controlled access mechanism where participants need permission or authorization to join the network and validate transactions.

Restricted Participation: Only approved participants can join the network, validate transactions, and participate in the consensus process. These participants may be required to meet certain criteria or follow specific rules defined by the network.

Centralized or Consortium Control: Permissioned blockchains are often controlled by a central authority or a consortium of multiple organizations. These entities have the power to make decisions and enforce rules within the network.

Enhanced Privacy: Since permissioned blockchains involve a limited number of known participants, they can provide enhanced privacy features, such as restricting access to transaction data or using encryption techniques to secure sensitive information.

2.Permissionless Blockchain: In contrast, a permissionless blockchain, also known as a public blockchain, is open to anyone who wants to participate in the network. It allows anyone to join the network, validate transactions, and participate in the consensus process. Key characteristics of permissionless blockchains include:

Open Access: Permissionless blockchains have an open access policy, allowing anyone to join the network, create transactions, and become a validator.

Decentralization: Permissionless blockchains are typically decentralized, meaning there is no central authority controlling the network. Instead, consensus is achieved through a distributed mechanism, such as proof-of-work (PoW) or proof-of-stake (PoS).

Transparency: Transactions and data on permissionless blockchains are transparent and visible to all participants. Anyone can inspect the blockchain's history and verify the integrity of transactions.

Public Validation: Consensus is reached by most participants in the network, typically through a consensus algorithm. Validators compete to solve cryptographic puzzles or stake their tokens to secure the network.

Examples of permissionless blockchains include Bitcoin and Ethereum, where anyone can participate, mine or validate transactions. Permissioned blockchains, on the other hand, are often used in enterprise settings, where specific participants need to collaborate and share information within a controlled environment.

Both permissioned and permissionless blockchains have their own use cases and advantages, depending on the requirements of the application or organization using them.