Intel Core i5 6400 's Advantages
Newer PCIe version (3.0 vs 2.0)
Higher base frequency (2.7GHz vs 2.0GHz)
Intel Celeron J4125 's Advantages
Released 4 years and 2 months late
Higher specification of memory (2400 vs 2133)
Larger memory bandwidth (38.4GB/s vs 34.1GB/s)
Lower TDP (10W vs 65W)