My understanding is that hierachical regression can be used to control for variables known to predict the DV by entering them in the first step. A hierarchical linear regression is a special form of a multiple linear regression analysis in which more variables are added to the model in separate steps called “blocks.”

e.g. Multiple hierarchical regression : First I would do a multiple regression to test the 4 levels of the IV.

In the context of multiple regression: a moderator effect is just an interaction between two predictors, typically created by multiplying the two predictors together, often after first centering the predictors. Step 1: age, gender (control for these)