They are similar in the way that you have to find the area of the base(s) and then the area of the lateral faces. They are different because there are different formulas used to derive their respective surface areas, and the calculations are a bit different as in a triangular prism, you have to find the area of some triangular faces, while the rectangular prism has all rectangular faces. Additionally, the triangular prism has 5 faces, and the rectangular prism has 6 faces. I hope this helps.
