OpenVZ or KVM is more like a dedicated server?

With OpenVZ the resources like memory (RAM) can be shared by different users. The term often used is called “burst” RAM or memory. If one or a few users are using a lot of resources than they can impact your VPS’s performance. With KVM the memory/RAM commited to your VPS is only available to you. A KVM VPS behaves a lot like a dedicated server than a OpenVZ VPS.

KVM VPS = dedicated resources + more freedom in installing Linux, *BSD, or Windows operating sytems

OpenVZ VPS = resources are shared among different hosts + limited to only Linux distributions

A dedicated server has more memory and CPU power compared to a typical KVM/OpenVZ VPS plan. Neither a typical KVM or OpenVZ VPS is really closer to a dedicated server but in terms of resources and isolation of resources than the answer would be KVM.