json.Unmarshall takes a pointer as its second parameter. In (1), a pointer to thing is created using &. In (2), thing is already a pointer and can be passed as-

json.Unmarshall takes a pointer as its second parameter. In (1), a pointer to thing is created using &. In (2), thing is already a pointer and can be passed as-is. They're semantically the same. The type of thing isn't, but that's syntax.