Difference between black and green cardamon?
Yes, a very big difference. If the recipe calls for green, get green. Green cardamom is one of the most expensive spices on the planet for a reason.
"There several related plants in genera Amomum, Aframomum and Alpinia, many of which have aromatic seeds; these may appear as cardamom substitute or adulteration, although the flavours of most of them differ markedly from true cardamom. Some of these have a eucalypt-like flavour worth dealing with in their own right (see black cardamom)"