The decentralized payment network is covered in full in the entry Decentralized Payments Platform, which explains how such systems move money, who runs them and how they compare with card schemes and bank transfers. This page gives a short definition and explains the different names.
A decentralized payment network is a system for sending value in which payments are validated and passed along by many independent participants rather than by a single company, bank or clearing house. Most run on a public blockchain or on a layer built on top of one. Examples include payments sent directly on the Bitcoin blockchain, the Lightning Network of payment channels, and transfers of stablecoins across public chains, described under stablecoin payments. Supporters point to round-the-clock settlement, lower costs for cross-border transfers and resistance to censorship; critics point to volatility, uneven consumer protection and compliance challenges.
"Network" tends to describe the underlying infrastructure of nodes and connections, while "platform" often refers to the services and applications people use to pay through it. In practice the two names describe the same idea, which also overlaps with blockchain payments and with open protocols such as the Interledger Protocol.