The line between impulse response and cab sim is a little blurry, but typically a cab simulator is used with an actual guitar amplifier, whilst an impulse response will be used with an amp simulator or a floor modeler like the Quad Cortex, Helix, Kemper, or Axe-FX. They both do a similar thing but the use case is ever so slightly different.
You can use an impulse response with a proper tube amplifier head, but you’ll need a reactive load to simulate your amp being plugged into a cabinet before you send it to the IR. This is because if you use an amp head without the correct speaker, you can potentially damage it. The same isn’t true of a solid-state amplifier, so these are fine to be connected straight to an impulse response loader.