The Key Difference: Restrictive vs. Non-Restrictive
The key difference between defining and non-defining relative clauses lies in their function within a sentence:
* Defining relative clauses: They define or restrict the noun they modify, providing essential information to identify it. They are essential to the sentence's meaning and are not set off by commas.
* Non-defining relative clauses: They add extra information about the noun they modify, but don't define it. They are not essential to the sentence's meaning and are always set off by commas.
Let's break it down with examples:
Defining:
* The book that I bought yesterday is on the table. This sentence implies that the speaker has multiple books, and the "that I bought yesterday" clause clarifies which specific book is being referred to. Without it, the sentence would be ambiguous.
Non-Defining:
* The book, which I bought yesterday, is on the table. This sentence implies that the speaker only has one book, and the "which I bought yesterday" clause simply provides extra information about it. The sentence would still be clear and unambiguous without the clause.
Key Differences:
| Feature | Defining Relative Clause | Non-Defining Relative Clause |
|----------------|-------------------------|------------------------------|
| Function | Defines or restricts the noun | Adds extra information |
| Necessity | Essential to meaning | Not essential to meaning |
| Commas | No commas | Commas are always used |
| Pronouns | who, whom, whose, that, which | who, whom, whose, which |
Important Note: While "that" is generally used in defining clauses, "which" can also be used in both defining and non-defining clauses.
Remember: Understanding the difference between defining and non-defining relative clauses is crucial for clear and accurate communication.