"VPN" is just virtual emulated network cables that you would use to connect your laptops to Wi-Fi routers. It's just so happens that a lot of companies use that word for a paid, cloud based Internet-over-Internet service. It's as if taxi companies called themselves "wheels" companies that whether you're referring to the physical object or the service had become ambiguous.

VPNs are normally processed in software, and that processing is usually multi-step. So latency, jitter, processing time per types of packets, etc can vary. This is FPGA based, and FPGA can run some algorithms and programs that can be implemented as chained conditions at fixed latency without relying on function calling in software. Presumably this is faster and more stable than software approaches thanks to that.