Comment by Zak

Highly variable based on load and the specific batteries involved. Alkaline will almost always have more capacity for something that takes more than a day of continuous operation to drain the battery, and NiMH will almost always have more for something that takes less than four hours.

Here's a tool you can use to compare different batteries at different loads, graphing voltage vs Amp-hours. The individual battery tests have more detail and graphs of voltage vs Watt-hours, which is often a more useful measurement.

https://lygte-info.dk/review/batteries2012/CommonAAcomparato...