Two different solids are shown in figure.
1) A cube of side, 4 cm.
Volume of cube = side * side * side = 4*4*4 = 64 cm cubic centimeters
Surface area of cube = 6 *side * side = 6 *4*4 = 96 cm^2
2) A rectangular prism of dimensions, l =8cm, h= 4 cm and b =2 cm
Volume of rectangular prism = side * side * side =8*4*2 = 64 cm cubic centimeters
Surface area of rectangular prism = 2lb + 2bh + 2hl
= 2*4*8 + 2*8*2 + 2*2*4
= 112 cm^2
The volume of both these solids are same but the surface area is different because volume means holding/containing something while surface area depends on the area of each surface in the figure. The surfaces in the cube are squares but in rectangular prism, the surfaces are rectangles.