There aren’t many differences when it comes to these spaces. The main thing that they do have in common is that they provide a lot of light as there tends to be a large amount of glazing.
Orangeries tend to have a solid flat roof with a roof latern to allow light in. The walls can be a mixture solid and glazed which allows you to comprise between having the natural light and being able to use the perimeter for functional purposes. This type of build is ideal when you have a height restriction to comply with.
Oak garden rooms tend to be a pitched roof with a similar make as an orangery for the walls. Due to the pitched roof, garden rooms lend the opportunity to have impressive feature roof trusses to create spectacular vaulted ceilings. The connection to the house is normally very open which provides great entertaining and family space. Oak garden rooms are often used as kitchen extensions or dining rooms.
Oak conservatories consist of mainly glass whether it be a pitched roof or a flat roof. The walls are also fully glazed which gives a huge amount of light into the roof. Conservatories are not as popular as they used to be as our desire to be more efficient and greener with our energy use means that a fully glazed building doesn’t quite have the desired effect. .