The 750M is not 35-45 W it is more like 25-30W. That can just be guessed from total power consumption in the different activation states.
Without Turbo and at 925Mhz it is probably even below 25W.
The Razer Blade is insane but the cooling system is actually different. It draws fresh Air directly from underneath. Not the back like the Macs. It has two heatpipes on each side rather than one (Apple) and a bigger heatspreader (about twice as thick). That is about twice the heatsink area more or less even in the smaller 14" chassis.
That increases its cooling power probably by some amount. It also gets really hot and is really pushing it. In the name of ergonomics they should probably have kept it with a 960M or the new 965M.
But both of these Apple could use with small changes like a stronger power supply and some small tweaks if they really wanted to.
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The Razer is different and a simplistic design can just very easily look the same. Same as many thin notebooks are wedge shaped like the Air. If you don't put sharp corners on it it looks the same. And rounding some part of the bottom to make the whole unit look thinner than it is, is not something Apple invented. If you do that too, you can change little more than the color. Inside there is also not that much choice in how stuff can be arranged at such a small space.
All computer manufactures play lego with more or less the same parts. There are a couple notebooks that look quite similar to the Razer as well.