I don't think there's a Linux VPS plan available. Just Linux dedicated servers.
With both the VPS and dedicated servers, you have full control over the entire server environment. You can add users, install any software, configure it anyway you want to.
The big difference is with VPS, your entire server environment is on a single physical machine along with other people's server environments. Nobody can access each other's environments. But you are sharing physical resources -- hard disk, memory, CPU.
With a dedicated server, your server environment is on a single physical machine with no one else. So you get all the physical resources (hard disk, memory, CPU) to yourself.
