What is difference between Luminaires & lamp and ballasts?

Difference?

What kind of test are you taking?

There is no difference, or a huge difference, depending on your perception.

First perhaps if I offer some definitions:

Luminaire = lighting fixture, a device that hold lamps that provide illumination. If one is a fluorescent luminaire would contain the next two items to be completely functional.

Lamps = Often called Light bulbs, typically installed into a luminaire to make it functional

Ballast = a device, technically either a magnetic transformer or a solid state electronic unit ,that limits current flow and provides starting voltage for a fluorescent or High Density Discharge lamp.

So, having provided a description of each I will let you determine the difference, as that answer I cannot provide.