Intel Core i5 8257U 's Advantages
Better graphics card performance
Lower TDP (15W vs 45W)
Intel Core i9 9980HK 's Advantages
Higher specification of memory (DDR4-2666 vs DDR4-2400)
Larger memory bandwidth (41.8GB/s vs 37.5GB/s)
Higher base frequency (2.4GHz vs 1.4GHz)
Larger L3 cache size (16MB vs 6MB)