What's the main difference between a "suit" and a "costume?"

Native speaker’s answer
Rebecca
A suit can be two types of clothing: the traditional, structured clothing that you might typically wear to the office or at a formal event, or the type of suit that fits tightly to your body, like a bathing suit, wetsuit, or the Iron Man/Spider Man suit. Ex: I wore a black suit to my job interview. Ex: I have several swimsuits ready for my beach vacation. On the other hand, a costume is a set of clothes styled for a specific place, time period, or occasion. Ex: What is your costume for Halloween? Ex: I like your Joker costume! So you can see in the case of Mysterio's suit, it is both a costume and a suit!