The answer to 'difference between lighting installation' is that there are two main types of lighting installation: new construction and retrofit. New construction involves installing lighting fixtures and wiring as part of building a new home or addition, while retrofit involves upgrading or replacing existing lighting in an existing home.
New construction lighting installation typically involves more extensive electrical work, as the wiring and electrical panel must be installed from scratch. This can be more complex and costly, but it allows for greater flexibility in lighting design and placement. Retrofit installations are generally simpler and less disruptive, as they involve working with the existing electrical infrastructure. However, retrofit options may be more limited in terms of fixture types and placement.