The material of the carton is the sum of the areas of the six sides of the carton, that is, the surface area of the cuboid.

The materials of small cartons (excluding empty covers) are:

ab*2+ac*2+bc*2=2ab+2ac+2bc(cm2)

The materials of large cartons (excluding empty covers) are:

( 1.5a * 2b)* 2+( 1.5a * 2c)* 2+(2b * 2c)* 2 = 6ab+6ac+8bc

So:

(1) The material used to make these two cartons is * * *

(2ab+2ac+2bc)+(6ab+6ac+8bc)

=8ab+8ac+ 10bc(cm2)

(2) Large cartons use more materials than small cartons.

(6ab+6ac+8bc)-(2ab+2ac+2bc)

=4ab+4ac+6bc(cm2)