Larry,
230 volts at 15 Amps is only 4.6 horsepower. If that is the "max" it can draw it must be full locked rotor amps, not running amps. So it's more likely about 3 horsepower.
More important information is the cu ft output at 90 PSI.
Overstated horsepower figures are common in the industry.
Another clue is to look at the motor plate and see what it says. If it says SPL, it means it's less than advertised on the compressor spec sheet. If it says 5 Horsepower, it means 5 running horsepower.
People should buy the biggest compressor they can afford and have power to run, for a shop, or match the output in CFM to the tool they want to operate. 18 CFM at 90 psi will comfortably run a 12 CFM tool at 90 psi, etc.
And single stage compressors will generally put out more CFM in the practical working range, than two stage compressors. Two stage is for working pressures over about 130 lbs.
I just hate all the misleading advertising that goes on.