You are mixing the term "power" with the term "energy". They are not the same thing. If a laser has a very short pulses, it could have very high peak power, and yet not all that much energy or average power transmitted. OTOH, if it's a continuos laser, then the average power is the same as the peak power. Power is in watts, energy in joules (watt seconds) Thus the 50 watt laser, if continuous, delivers 50 joules every second. But if the laser has a microsecond pulse at the rate of one pulse per second, then it would take a 50 Megawatt peak power to deliver the same average power, or energy per second.
Off-point. I already addressed that in a previous post.