Check Point Appliance Hardware (Lachmann List, 28 Feb 2017) :
3200 - 1x Intel Atom C2558, 2.40GHz (Quad-Core)
5200 - 1x Intel Celeron G1820, 2.70GHz (Dual-Core)
5400 - 1x Intel Pentium G3420, 3.20GHz (Dual Core)
Comparison of these three: Intel® Product Specification Comparison
I wouldn't say that Intel Atom is better (more powerful) CPU than Intel Celeron or Pentium, just the number of cores is bigger in this case. But there is also a difference in terms of form factor, placement of appliances, cooling, LOM card, RAM options, etc., which could be important for some customers.