The difference is quantitative, but multiple magnitudes big: The ratio of impulse to mass is given by the exhaust velocity, and velocities for massive propellan

The difference is quantitative, but multiple magnitudes big: The ratio of impulse to mass is given by the exhaust velocity, and velocities for massive propellants barely reach 0.01% of the speed of light. Thus the thrust can be more than 10 000 times higher for the same propellant mass. On the flip side, the exhaust velocity also determines the ratio of (kinetic) energy to impulse, so energy beam propulsion needs over 10 000 times more stored energy. Energy beam propulsion is only viable if you have compact high-capacity energy storage available (antimatter?).