Both pieces are the same clay, same glaze. The one on the left went to cone 4. Notice how full of holes and bubbles the glaze is. The one on the right went to cone 6 using the C6DHSC firing schedule. It is perfectly smooth and glassy.
A kiln firing schedule where temperature is eased to the top, then dropped quickly and held at a temperature 100-200F lower.
Loss on Ignition is a number that appears on the data sheets of ceramic materials. It refers to the amount of weight the material loses as it decomposes to release water vapor and various gases during firing.