There are regional differences that are probably causing some confusion. In the US, breakers have a nameplate rating 25% higher than their continuous load capacity. Go to Australia, for example, and the identical breaker will have a nameplate rating 80% of what it would in the US.

So you can run indefinitely at the nameplate rating in Australia, but only 3 hours in the US. And the startup current (inrush) can be much higher than the rating. Most breakers are thermo-magnetic. The magnetic part has a much higher tripping point and allows for inrush current. The thermo part trips when it gets too hot, and that'll be the current printed on the breaker.