As we’ve learned with pimples and cold sores, certain skin ailments can prove difficult to tell apart. So often when a red bump or pus-filled pustule appears, we have a tendency to automatically assume it’s some form of acne and treat it as such — or we just wait it out and pray it goes away. But in reality, said red bump can be a multitude of things, including the aforementioned cold sore, so it’s crucial to know what you’re working with in order to properly treat it.Take styes and milia, for instance. Both are common skin woes that, because of their blemish-like appearance, are quite often confused with pimples or another form of acne, such as whiteheads. Because of how close the three ailments are in appearance, we tapped a few trusted dermatologists for a definitive breakdown of styes, pimples, and milia — and how to effectively ward off each.