 0.The Death Star's Laser broke the crust of the planet and heated the core to the point where enough energy was released to destroy the planet,The Death Star also had unimaginable numbers of turbolaser banks and other defenses, Rebel ships had excellent pilots,even then they took heavy losses. You would be surprised to see how much development went into weapons. Its not like during the clone wars everyone said "WELP, I GUESS ARE GUNS ARE GUD ENUF. HERP A DERP" They were ships from the same era fighting each other,So obviously they will be on par with each other ,but if a Venator took on A Star Destroyer,The Star destroyer would win hands down! 