l
        b
        h
        
         Surface Area of a Cuboid = $2(lb + bh + hl)$. 
where $l$ = length , $b$ = breadth and $h$ = height of cubiod.
In a cube , l=b=h , hence surface are of cube = $2(l×l + l×l + l×l)$
= $6l^2$
Suppose, out of the six faces of a cuboid, we only find the area of the four faces, leaving the bottom and top faces. In such a case, the area of these four faces is called the lateral surface area of the cuboid.

So, lateral surface area of a cuboid of length $l$, breadth $b$ and height $h$ is equal to

         
Lateral Surface Area of cuboid= 2lh + 2bh or 2(l + b)h.