In forecasting, there is a very common point forecast accuracy measure, the Mean Absolute Error (MAE) or Mean Absolute Deviation (MAD), which simply calculates the mean absolute difference between point forecasts and the corresponding actuals.
However, the term "MAD" is also used in non-forecasting statistics, specifically in descriptive statistics, to denote the spread of a distribution by calculating the Mean Absolute Deviation between the distribution and (say) its median.
I have just created an mae tag, put in a tag wiki & excerpt, and edited the mad tag, suggesting that posters use mae if they are asking about the point forecast accuracy measure. I have also started to retag a few questions and will retag some more over the next days, to avoid bump-flooding the landing page.
No, there is no question as such here - this is more of a public service announcement (plus an attempt to raise awareness about the different tags, and an explanation we can send people to who wonder about the two similar tags in the future).