Intel Core i5 6400 's Advantages
Larger memory bandwidth (34.1GB/s vs 29.9GB/s)
Newer PCIe version (3.0 vs 2.0)
Higher base frequency (2.7GHz vs 1.5GHz)
Intel Celeron J3455E 's Advantages
Released 3 years and 10 months late
Higher specification of memory (LPDDR4-2400 vs DDR4-2133)
Lower TDP (10W vs 65W)