Intel Core i5 8400 's Advantages
Higher base frequency (2.8GHz vs 2.1GHz)
Intel Core i7 14700 's Advantages
Released 6 years and 3 months late
Better graphics card performance
Higher specification of memory (DDR5-5600 vs DDR4-2666)
Larger memory bandwidth (89.6GB/s vs 41.6GB/s)
Newer PCIe version (5.0 vs 3.0)
Larger L3 cache size (33MB vs 9MB)
More modern manufacturing process (10nm vs 14nm)