It varies wildly on the simulator. Boeing or Airbus are completly able to rehost their software on a simulator mostly made from real OEM parts. From that, it's simply a matter of designing new scenarios from what you're feeding the various sensors.

On the other hand, if you're simply looking for some training hours on some specific basic scenario and/or aircraft, the simulators can be a lot rougher and still be certified. I "flew" on an airliner manufacturer designed simulator, and everything from the instrument panel to the hydraulics simulating the small impact when rolling between plates on a concrete runway felt pretty damn real.

For more basic stuff, even X-Plane exists in an FAA-approved version.