Image_Friend is a fraud who does nothing yet seems important. Would say they're like Golden Freddy (another fraud) although Golden Freddy's more like The Roaring Knight (both Golden Freddy and The Knight both have little sisters and come from rich families, if you believe Dave co-possesses Golden Freddy while Dess is the Knight)
NormalNPC pretends to be and acts like a total nothingburger, yet
TL;DR: Image_Friend is all bark no bite, The Roaring Knight is mostly bark and some bite, NormalNPC is no bark all bite.