The angled side is great for filling in sparse areas of the brows or creating thicker more defined brows, while the spoolie side is great for grooming the brows.
The angled end of the brush has more than one use. Stipple the brush into an eye shadow lighter than your brows if they are dark, and a shade darker if you have light brows. Using short strokes fill in your brows until you achieve the desired look. The angled end is also perfect for placing color on the top of your lash line and underneath the eyes for a smokey look.
Use the spoolie end after you have filled in your eyebrows to help soften the appearance of the brows and blend out any harsh lines or strokes. It can also be used to brush your eyebrows into place laying down any fly away hairs, and to help separate lashes after you have applied your mascara.