Tizen Emulator is closer to the actual device because does an actual emulation so it has an OS image build on it.

Web Simulator is simulating the API, the Web Runtime, and some of the connectivity using Chromium's Webkit engine. It is a simulated environment and there is support only fort the HTML5 applications and not for the native applications.

From my experience with the Tizen Web application API, Tizen Emulator was closer to the actual device compared with the simulator.