Cycles Render: Translucent and Glass (roughness=1)

Why there is translucent material in Cycles Render?

the glass is translucent by definition so it’s not a big surprise, it’s like saying that an apple is a fruit; talking about Cycles, the glass material has its own settings about the method ( GGX, Beckmann and Sharp ) and the IOR, and this is a big difference with the translucent one that only has a color.