A greenhouse is normally characterized by the following:
A building largely made up out of framing and glass panels
A building that has been made economically and with an eye for keeping costs low.
A building which main purpose is the growing of and the caring for plants
Often a free-standing building not attached to other types of buildings
This is in contrast with a conservatory, a building that is often confused with a greenhouse as the main purpose of a conservatory is to be used as a living space, with plants sometimes intermixed.
A few examples of a greenhouse are the following:
A large building on a farm filled with rows and rows of plants being grown for consumption or sale.
A small building in a private garden or allotment garden used mainly for the growing of plants.
A building that is of the same type of either of the two described above but is empty or used for the storage of other objects is still a greenhouse as well.
A botanical garden can also be called a greenhouse although it often overlaps with a conservatory.
