Difference between installing Orchestrator, installing Orchestrator Server, and using the Web App?

I have a conceptual question here. I am trying to set up two VM’s such that I can run a robot on one by accessing orchestrator on the other. When I do research for orchestrator, I am having trouble identifying which method of installation I should use. I was wondering if someone could explain the difference between these three things:

  1. Installing the orchestrator website: https://orchestrator.uipath.com/docs/the-windows-installer

  2. Installing the orchestrator server: https://orchestrator.uipath.com/v2016.2/docs/orchestrator-server-installation

  3. Using the orchestrator website: https://platform.uipath.com/account/login?returnUrl=%2F

I’m probably just uninformed, but I’m really confused on this and would greatly appreciate any help. Thank you all!