Finding the volume of a figure means finding how much of a unit can fit within that figure. You can find the volume of a figure by multiplying L x W x H. Finding the surface area of a figure means how much area there is on a figure. You can do this by finding each side's area, then add the side's areas together. (If you are finding surface area of a cube, it is 6(L x W). For a rectangular prism, it is a(L x W) + b(L x W).) Basically, the math behind the answer is what makes these two things different.
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Hope this helps. Have a nice day.