The only true deference between the 3rd gen and 4th gen CPUs are power consumption, the 4th gen CPU's are better for laptops because they will extend your battery life of the laptop, Also Haswell is 10% over all over the 3rd gen CPU's but in real world performance the end user will not be able to tell a true difference between the two chips.
If you are doing projects like video editing/rendering, 3D rendering or graphic designing then the i7's are great for those types of application but when gaming the i7's because of hyper-threading can hurt your FPS in games as almost no game on the market to date utilizes hyper-threading.
If your parents have already bought the 3rd gen i7 laptop then I would not be disappointed for not getting a 4th gen i5 Laptop but if you are still looking and have not purchased the laptop yet, then I would go with the i5 4th gen laptop.
How to differ by Logo
