Intel Core i5 8279U 's Advantages
Better graphics card performance
Lower TDP (28W vs 45W)
Intel Core i5 9400H 's Advantages
Higher specification of memory (2666 vs 2400)
Larger memory bandwidth (41.8GB/s vs 37.5GB/s)
Higher base frequency (2.5GHz vs 2.4GHz)
Larger L3 cache size (8MB vs 6MB)