In power usage, yes, 2 50s equal one 100w. But for what we want you need to look at the lumen count. THAT is the number that matters, the bigger the better. The lumens are the amount of light that bulb puts out.
Sort of like HP in an engine. Cu inches mean nothing but bigger consumption. If I can make twice the HP with a smaller engine, I have better bang for the buck so to speak.