What is the difference between a VPN and a DVPN?

Can you explain the fundamental differences between a Virtual Private Network (VPN) and a Decentralized Virtual Private Network (DVPN)? I'm curious about how they differ in terms of their operation, security, and the level of control they offer to users. How does the decentralization aspect of DVPNs impact their functionality and reliability compared to traditional VPNs? Additionally, what are some potential advantages and disadvantages of using a DVPN over a VPN?