Student or Learner
Are greenhouse and hothouse the same?
In fact, some gardeners, on a programme on BBC radio called Gardeners' Question Time, ask questions such as 'I have been gardening with a cold greenhouse for several years, but now I want to install electricity...'.
I don't often hear the word 'hothouse' - except in the idiom 'hothouse plant' [=delicate and/or temperamental person] - and I think it may be falling out of use. But if I heard it I would understand that it referred to a greenhouse that incorporated some form of heating.
I would interpret 'hothouse' to mean some type of sauna or steam room. I wouldn't think of it as referring to a heated greenhouse.
In the horticultural world/industry "hothouse" is commonly used to describe a heated greenhouse.
A hothouse means a heated greenhouse to me too. I have never heard it used to describe a sauna or a steam room.