Power requirements for hot tub (reading from label)
Looks to me like it needs both 120V and 240V. 

The 120 is likely for the water pump and controls while the 240 is for the water heater.

Here is a typical wiring diagram for a SPA.



As for what the various current ratings are for on the 240 it is difficult to know without more information. Different heaters for different sized units perhaps, or different heat settings if there are any.