Phew, I have to admit, I don't know what the difference is. We are having the house built turnkey by a "house building company," the land comes from us.
Then it is a general contractor or main contractor. The builders, with all rights and obligations, are yourselves.
You should take out building insurance, the fire shell construction insurance is (practically always?) included then. Upon completion/move-in, the insurance automatically converts into the building insurance. Until then, it runs as fire shell construction insurance.
Do you have a fixed price including all additional costs? Before concluding the insurance, you should indeed study the construction and performance description thoroughly.