"Her entire dress was trimmed in gold braid. Pink pearl earrings adorned her tiny earlobes. But it was her crazy headgear that proved she was a princess: a glittering tiara, studded with what appeared to be real diamonds, rubies, emeralds and blue stones. Sapphires, I guess."

That's how soccer playing Casey Peabody describes her first surprising glimpse of Princess Eglantine of Trewellyn. You wouldn't expect Casey to know much about sapphires, or tiaras.

Wouldn't she wear a crown? Thankfully, I can't remember which of my friends or acquaintances asked me that question, hinting that I didn't know a tiara from a top hat. (I do. Top hats aren't glittery at all.)

The answer is no, Princess Eglantine wouldn't wear a crown. She'd wear a tiara.
While some people use the words interchangeably, there is a difference.
A tiara is a type of crown. It's usually distinguished by a high crown, narrower at the top. We usually think of it as a semi-circular band (in contract to a fully round crown), that is adorned with jewels. They can be diamonds or any assortment of precious stones. (Or fake ones, let's get real!)

However, the owner of the largest and most valuable collection of tiaras in the word is - ta da! - Queen Elizabeth. Usually, though, she wears a large hat.

Speaking of queens, here's a picture of Queen Alexandra, wife of Edward VII of Great Britain (seated) wearing a crown, while her daughters are wearing tiaras. See the difference? Tiaras don't weigh as much and don't give you hat-hair. And they're easier to keep on your head. You wouldn't want to go to a dance wearing a crown but you'd do just fine with a tiara.

So Princess Egg, as the Princesses above, wears a tiara. Proudly and confidently, I might add! If she ever returns to Trewellyn and becomes Queen, she would wear a crown at her coronation.

But these adornments aren't only worn by royalty or beauty pageant winners.
Here are a few surprising tiara-wearers:
Wonder Woman - she never left home without one and it never ever fell off
Sailor Moon - I think that's a tiara, just different
The Pope - I'm not making this up. There is a cap called the Papal Tiara. It's a high cap surrounded by three crowns, with a globe and a cross. It hasn't been used by the last few popes.
Many brides now wear tiaras at their weddings