Do dark lines on porcelain dishes indicate usage of aluminium for the color?
If the two bowls look different although treated similar, the material must differ.

Your bowls are almost fully covered with a glaze - except for the ring on the bottom on which the ceramic was standing while fired in an oven. 

Here, water can enter the ceramic core. If the ceramic material of one bowl is more porous, water can be taken up easier. Upon heating, as in a dishwasher, the water absorbed expands. The glaze can't withstand the tension build up and breaks. 

This results in the cracks that you observe.