I learned how to apply eye shadow by watching makeup gurus on YouTube, if you hadn’t already noticed. I have learned tricks that I might have not grasped by simply reading the description on a makeup brush’s packaging. Sometimes brushes can be a substitute for the “proper” brush, like using a blush brush to add highlights (which I do). And some brushes are versatile, especially those used for applying eye shadow. For instance, an angled eyeliner brush can be used to apply liquid eyeliner or create a clean line of eye shadow (provided you wash it before switching over).
Shadow Brush: ideal for applying shadow to the lids (always pat, never smear).
Crease Brush: for placing shadow in the crease around your eyes.
Smudge Brush: can be used to blend two colors already on the lids or soften pencil eyeliner.
Eyeliner Brush: can be used to create outlines of eye shadow so things don’t get out of hand or for liquid eyeliner.
Contour Brush: similar to the crease brush but more concentrated shadow application (not blending it out as much, helps add definition in the crease).
Blush Brush: for the cheeks (I hope you mean your face!). Although I use the second one to apply highlighter when I’m contouring my face.
Hope that helps! : D