What is the difference between the DDJ-SB3 and the DDJ-400?

The DDJ-400 is a model optimized for DJ performances using rekordbox dj. rekordbox dj is included, and the unit is equipped with optimal operation interfaces for operating it.
Whereas, the DDJ-SB3 is a model optimized for DJ performances using Serato DJ Lite. Serato DJ Lite is included, and the units are equipped with operation interfaces in an optimal layout for operating it.