Why does the max charge reported by battery health app differ from the "Full Charge Capacity" in About This Mac > System Report?

In System Information > Power it says

Charge Remaining (mAh): 5179
Full Charge Capacity (mAh): 5432

But Battery Health 2 reports a Current Charge of 4952mAh and a Current Max of 5097mAh.

Why are they different?

The charge can be 100% as shown.

However the health is based on the available capacity now compared to the original capacity when the battery was new. The charge holding capacity degrades over time.

So the 100% charge is 100% of the current capacity.

So, having missed the bit about comparison, the difference can be due to the system not having had an smc reset recently and the results can tend to drift over time. fwiw I have found that battery apps can give a good account with more detail, but if the system says it will shutdown at a certain value then it will be based on the system’s recorded value.