Lineal feet is the same are feet. There is no difference. If something is 4 lineal feet tall, its 4 feet tall. You haven't mentioned the 2nd dimension of it. Square feet is an area. We must know the width. E.g. If you have 8 lineal feet of steel, and its width is 1 foot, you have 10 X 1 = 10 square feet of steel.
