AMD Ryzen 7 7840U's Advantages
Better graphics card performance
Higher specification of memory (LPDDR5x-7500 vs DDR5-5200)
Higher base frequency (3.3GHz vs 3.0GHz)
More modern manufacturing process (4nm vs 5nm)
Lower TDP (15W vs 45W)
AMD Ryzen 9 7845HX's Advantages
Newer PCIe version (5.0 vs 4.0)
Larger L3 cache size (64MB vs 16MB)