Stars with masses below about 4 solar masses, stars produce white dwarfs as their end products. With masses above 15 solar masses, you end up with black holes. In the range between about 5 - 15 solar masses it seems you end up with either completely detonated stars and no end products, or neutron stars. My last encounter with the evolution of massive stars suggested that between 5 - 8 solar masses, a star evolves a core of non-degenerate carbon ash from previous ( triple-alpha) reactions. When this detonates the entire star is dissipated. But for stars between about 8 - 15 solar masses, the carbon core is degenerate like a white dwarf, and when the explosion happens, most of the energy goes into lifting the degeneracy condition of the dense, compact matter, and so the star survives 'carbon detonation' and becomes a supernova with an imploded dense neutron core. So, there seems to be a 'tierra incognita' between perhaps 5 - 8 solar masses where a star explodes and leaves nothing behind, followed by a brief interval where neutron stars are left behind, and a broad higher mass regime where black holes are produced. The critical masses are not really know with great precision because they depend on many details of the stellar composition and internal thermodynamics. All we can say is that neutron stars are probably first produced near a mass of ABOUT 8 solar masses. But 6 solar masses may be possible, and 10 solar masses too.