so hmm notice the picture below
a rectangular prism, is just 6 rectangles stacked up to each other
so... to find the Surface Area, just get the area of each rectangle, notice is 3 pairs of similar rectangles, so, get their area and sum them up, that's the Surface Area of the rectangular prism
now, the Lateral Area, is just the area of the sides, laterals, so, that means, just get add up the areas of the rectangles upfront, on the back, and the ones on left and right sides, that's the Lateral Area of the rectangular prism.