Intel Core i3 9100 's Advantages
Lower TDP (65W vs 125W)
Intel Core i7 12700K 's Advantages
Released 2 years and 6 months late
Better graphics card performance
Higher specification of memory (4800 vs 2400)
Larger memory bandwidth (76.8GB/s vs 37.5GB/s)
Newer PCIe version (5.0 vs 3.0)
Larger L3 cache size (25MB vs 6MB)
More modern manufacturing process (10nm vs 14nm)