Depending on the generation but i5 vs i7 has larger difference (number of cores) and i7 vs i9 is mostly clock speed. Also there are factors like battery consum

Depending on the generation but i5 vs i7 has larger difference (number of cores) and i7 vs i9 is mostly clock speed. Also there are factors like battery consumption. The lower-end CPU uses less power so the battery lasts long. Same can be said for GPUs but if you play games you probably want NVIDIA GPU even though it is worse battery-wise.