What is the difference between their and their?

I believe there might be a mistake in the question you provided. It seems that you have mentioned "their" twice. However, I assume you intended to ask about the difference between "their," "there," and "they're."

Let's explore the meanings and usage of these three words:

1. Their: "Their" is a possessive pronoun used to indicate ownership or possession by multiple people or things. It is the plural form of "his" or "her." For example, "Their house is beautiful" means that the house belongs to a group of people.

2. There: "There" is an adverb used to indicate a place or location. It can also be used to introduce a sentence or clause. For instance, "The book is over there on the shelf" indicates the location of the book.

3. They're: "They're" is a contraction of "they are." It combines the pronoun "they" with the verb "are." It is used to describe a group of people or things. For example, "They're going to the park" means that a group of individuals is going to the park.

To summarize:
- "Their" indicates possession by multiple people or things.
- "There" refers to a place or location.
- "They're" is a contraction of "they are" and describes a group of people or things.

It is important to note the distinction between these words to ensure clear and accurate communication in writing or speaking.