Intel Core i5 8259U 's Advantages
Higher base frequency (2.3GHz vs 1.6GHz)
Lower TDP (28W vs 57W)
Intel Core Ultra 5 135U 's Advantages
Released 5 years and 8 months late
Better graphics card performance
Higher specification of memory (7467 vs 2400)
Larger memory bandwidth (120GB/s vs 37.5GB/s)
Newer PCIe version (4.0 vs 3.0)
Larger L3 cache size (12MB vs 6MB)
More modern manufacturing process (7nm vs 14nm)