Main categories
There are two main categories that stage lights fall into. Headlights illuminate a wide area, and the headlights illuminate a less specific area.
Scoop Lights
These lights are usually used to flood the scene from above because they have the least focus. They are also the cheapest lamps because they have no lenses.
PAR Lights
These are headlights that are housed in a can-shaped container that is attached to a swing. This allows them to be moved when needed, making them suitable for mating with effects such as smoke machines.
Fresnal Lanterns
These lamps are a type of headlight. They offer a narrow focused area with soft light that can be used to properly tone an actor or object on stage.
Ellipsoidal Reflector Spotlights
These headlights have a much brighter and harder light. They are what are most often considered as headlights and are used to draw attention to whatever they are shining. Stage lighting is important for games, concerts or on stage. It also composes one of the most technical and complicated systems in a theater. There are a number of different types of stage lights, each with its own function and purpose. They work together to properly light an action, and the whole system would not be the same if one of these lamps was taken out of rotation.
Source:danspela.com