Answer:
Cuboidal cells are thicker than squamous cells. Cuboidal cells are usually where a function of absorption or secretion is need.
Squamous cells are usually laid in a single layer making the layer thin. This is useful because this type of arrangement allows for diffusion to happen and its used where diffusion is the main type of transport. Remember that the rate of diffusion slows down with distance. In the lungs gas exchange needs to happen very fast to keep a constant supply of oxygen to the lungs. Cuboidal cells would be too thick.