How does this scenario demonstrate the transformation of mass into energy as given by Einstein’s equation E=mc^2?

Question

when hydrogen is fused into helium , whether in the sun or in the nuclear bomb, the mass difference is turned into energy. 

Answer 1

One He nucleus consists of 2 protons and 2 neutrons bound together.  But if you look up and add the masses of 2 protons and 2 neutrons, and compare it to the mass of a helium nucleus, the mass of the nucleus is actually slightly smaller than the sum of the masses of its 4 parts.  During the process of fusing H, some mass was converted to energy and the energy was released, leaving behind a slightly smaller mass than the sum of the masses of the particles that were fused together.