Ghost Koi are a cross between Mirror or Common Carp and Koi Carp. They are hardier than Koi and can be faster growing.
They generally have a creamy head and cream colour along the body although you can now get other colours depending on the parent Koi.
They will grow large and fast and, although they are very hardy, they are also very messy and will easily uproot plants as they get bigger. They will also eat a lot and produce a lot of waste so bear water quality in mind. The pond should either be very large or well filtered (preferably both).