Quote Originally Posted by Geoffrey S
The principle of creation is similar (ie. large star collapses inwards to form a far smaller area, creating a hugely dense object) but they aren't made of the same material. The core of a neutron star consists of neutrons, but I'm not sure what a black hole is made of; anything at such high densities is purely theoretical, since it can't be recreated here on earth.
That could be the reason some people think it's made of Dark Matter. Supposedly this theory is validated mathematically, although I'm not sure how it is.