A protocol that allows anyone to join network and feature a high level of decentralization, security, transparency, along with community governance. This is the Bitcoin protocol.
A protocol that requires authorization, and sacrifice decentralization for higher speed, scalability, and customization. As they are increasingly centralized, many in the community argue that permissioned blockchains go against the core principles of crypto.
DLT (Distributed Ledger Technology)
This is the technical terminology for blockchain.