Intel Core i5 7400 's Advantages
Integrated graphics card
Lower TDP (65W vs 140W)
Intel Core i7 7820X 's Advantages
Higher specification of memory (DDR4-2666 vs DDR4-2400)
Larger memory bandwidth (79.47GB/s vs 35.76GB/s)
Higher base frequency (3.6GHz vs 3.0GHz)
Larger L3 cache size (11MB vs 6MB)