Forex VPS is a specialized server created for the sole purpose of running forex trading-related software like MetaTrader. Windows VPS on the other hand is a server configured for the sole purpose of running Windows OS-related software.
Both Forex and Windows VPS can be used for trading, the major difference lies in the performance.
Since Forex virtual private servers are configured and dedicated for running trading software, they tend to perform significantly better than Windows VPS for trading purposes.
Windows VPS would be a better option when running non-forex or trading-related tasks.
Read more here: https://www.vpsmalaysia.com.my/blog/forex-vps-vs-windows-vps-whats-the-difference/