Blue stars are young stars. Their initial mass is very high as compared to the red main sequence stars. The mass fuels the fusion reaction inside the star.The red main sequence stars are towards the end of their lives. The fuel is used up. There is no more fusion reaction going on. The outer layer expands. So, these red giants and super-giants are massive in volume not in mass.
Answer:
Their initial mass is very high as compared to the red main sequence stars.
Explanation: