Well, a lot really, but here's one thing.
Here I have a stock symbol for an ETC Source 4 19° degree instrument and a Vectorworks Light Object-Spotlight. The Vectorworks Light is selected, so the OIP shows options available for that type of device. One thing to notice is that VWX refers to Spread and Beam which theatrical light designers typically call Field and Beam. There are many options for 'focusing' a Vectorworks Lighting Object, both manually and through the OIP.
You can select the Spotlight Lighting Device for yourself and see the myriad of options available. I expect everyone reading this has probably done that at least once.
Both lights show up in the Visualization palette as well. By default, the Vectorworks Light Object is turned on and the Spotlight lighting device is turned off. You can turn that Device on here or by right clicking and selecting Turn On from the contextual menu.
Right clicking on the Spotlight Lighting Device also allows you the option of Editing the Light. Let's look there. The resulting dialogue shows you a bit of the Vectorworks Lighting Object that is imbedded in the Spotlight Lighting Device. Most of the options are greyed out.
We'll get to those details in another post.
This dialogue does allow you to do a number of things, You can assign a color, or if you have assigned a color in the OIP, it will show up here. This is where you can assign a level when visualizing and it is also where you can tell the Device to light up any fog you have specified in your Renderworks Background. Unfortunately, the Device does not really differ from Fog and Haze. Perhaps one day.
One key thing you can learn here are the specific Field and Beam settings for a particular unit. It is then possible to use those settings to adjust a Vectorworks Light Object, or to use that information to create your own custom Spotlight Lighting Device Symbol.
I like to use Vectorworks Light Objects for pre-visualization, that is before I've decided where to where to put each specific light. I can easily and very quickly lay down a blue wash with few Vectorworks Light Objects, set to a wide beam and possibly at more than 100%. You can do this with a Spotlight Lighting Device, but that's not going to help you in the long run.
So, if you know that you want an R80 wash and a narrow beam of L104, you can assign those colors to the Vectorworks Light Objects and you can create a Vectorworks Light Object with the same Beam and Spread or Beam and Field to get a quick look. Also, you can assign the Fog option as you like, perhaps only to the narrow beam so it really shows!