AMD Ryzen 3 5300U 's Advantages
Higher specification of memory (LPDDR4-4266 vs DDR5-5600)
Lower TDP (10W vs 35W)
AMD Ryzen 7 7840H 's Advantages
Released 2 years late
Larger memory bandwidth (89.6GB/s vs 51.2GB/s)
Newer PCIe version (4 vs 3.0)
Higher base frequency (3.8GHz vs 2.6GHz)
Larger L3 cache size (16MB vs 4MB)
More modern manufacturing process (4nm vs 7nm)