Irregulars units have some advantages in the game. However, I'm unsure about what units are considered irregulars.
Indians and "courriers" / rangers are irregulars, and if I'm not mistaken, so is light infantry ( and does this include light infantry from "regular" armies like French or British troops?).
But I'm really unsure about the most common units in the game : militias. Are these "regulars" or "irregulars"?