The power from a 120-watt laser is exactly the same as the power from a 120-watt incandescent lamp. The lamp gives off most of its power in the form of heat in all directions, and only some of the power in the form of visible light. The 120-watt laser doesn't give off much heat at all, but puts most of that power into one color of light, and it concentrates the power into a very thin directed beam.
In many respects, the 120 watt laser is concentrating that 120 watts into a very small area. Think of a fairly large magnifying glass. The magnifier concentrates the light from the sun into a very small area. That concentrated beam is very dangerous to ants. It is also dangerous to humans when the magnifying glass concentrates the beam on a person's hand. Of course, using the magnifying glass to fucus the light from the sun on a person's eye will permanently blind the person.
The concentrated light from a laser, though, isn't focused; the concentrated light from a laser is the same size no matter how far the light travels from the laser. In other words, the emissions from a laser are a very thin beam of light. The power inside that beam of light, no matter how far it is projected from the laser itself, is 120 watts; anything outside the beam of light from the laser doesn't get any emissions at all from the laser.
As far as danger goes, a 120-watt laser aimed at your hand will give you a very small, but very, very bad burn. Also, look into any laser, of any power, and will blind you.
If what your neighbor has in a commercially available laser cutting and etching machine, the laser is designed to only shine its beam of light into the machine. The machine is also designed to safely receive the beam of light. In other words, any commercially bought laser cutting and etching machine is safe.
It also will not be a danger to any neighbor.
Look at the Machine
Talk to your neighbor. See if you can get a tour. Express your concerns to the neighbor. You might be surprised with the results.