Hello John Williams,
Thanks for writing in.
Would you please tell us know what kind of load do you connect?

There are three kinds of power: Active power(P), Apparent power(S) ,Reactive power(Q)
The power we mention here is Active power.
For example:
The computational formula for Apparent power: S= U*I
The computational formula for Active power : P=U*I*cosφ(cosφ is power factor)

As different load have different power factor, the current and active power is also different.
For example, the cosφfor pure resistive load is near 1, so the Active power is almost near U*I ;
The cosφfor inductive load and capacitive load is between 0-1, so the Active power is less than U*I.

You can try to measure the power factor of load with multimeter.
For any more questions, just let us know.
Best regards.