"It fits you" = It's the proper size. Loose where it should be, tight where it should be, right length, etc. "It suits you" = It looks good on you and is the style that is best for you.

I like Lisa's answer, but I think "It fits you" can also mean "it suits you". The two overlap. "To fit" is a broad verb that applies to a huge variety of situations. For example, two people can "fit" as friends, meaning they are suitable friends for each other.

I am not sure why my comment violated community guidelines. I gave some good examples of using "it suits you" in contexts other than describing clothes. I am upset that they blocked my comment and did not even tell me what was wrong with it. I will be contacting iTalki support to get this straightened out.

Now I understand. Thank you all for clearing this up for me.

If it fits you it doesn't necessarily mean it suits you . Think of it this way. Most people would say they have a certain style of clothing they like to wear, something they are comfortable in. The people who know you best would see it as your style. But if you suddenly changed your style and started wearing clothing you don't normally wear you might feel uncomfortable and your friends might notice and tell you it doesn't suit you. That's not your style.