You don't give us much to go here, but assuming this is a pump being used to circulate chilled water within a closed loop.

Many pumps in this type of service have a high working pressure but a low differential head because in a closed loop all you need the pump to do is overcome frictional losses. However the static or hydro static pressure at the lowest point in the system might be quite high due to the elevation of the building.

So e.g. you have a building 100m high with a frictional losses of say 20m, then if your pump is located in the base then it will see 120m on the discharge but 100m on the inlet.

Pump bhp is the shaft power needed to run the pump. your motor bhp needs to be bigger than this to avoid overheating and burnout. Motor bhp often comes in jumps so the next lowest might only be 5kW. You always need some sort of margin in case the pump flows more water than you intended. Many motors are sized for "end of curve" operation which normally need more power than the "rated" condition.

Makes sense?

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item 2: probably the maximum designed working pressure for the pump.
item 3 & 4: 5.5kw is required power for operation, 7.5kw is to give margin for any upsets - as explained by Littelnch

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

Quote (op)

1) Pump Head: 200Kpa
2) Pump Working Pressure: 1600Kpa

This looks like the pump selection for a highrise tower with the pump located at the ground level or thereabouts.Pump outlet head is 1600 Kpa and Inlet head is 1400 Kpa.There is a static head of around 140 m(equivalent of 1400 Kpa) at the pump suction centre line.