Who vs Which: What's the Difference?

Understanding the distinction between “who” and “which” is essential for clear and precise communication in English. While both are used to introduce additional information about nouns, their application depends on whether the noun refers to a person or a thing. Clarifying this difference helps avoid ambiguity and improves the quality of your writing.

What Are “Who” and “Which”?

“Who” and “which” are relative pronouns used to introduce relative clauses—additional information that describes or identifies a noun in a sentence. They serve to connect ideas smoothly, providing clarity and detail. However, their usage hinges on the nature of the noun they modify:

“Who” is used exclusively for people or entities regarded as persons.

“Which” is used for animals, objects, or abstract concepts—essentially, non-human nouns.

For example:

The teacher who explained the lesson is very patient.
The book which I borrowed from the library is fascinating.

Key Distinguishing Factors

The primary factor that differentiates “who” and “which” is the type of noun they modify. Here are some concrete points to guide their usage:

Person vs. Non-Person: “Who” always refers to people or entities considered as persons. “Which” refers to animals, inanimate objects, or abstract ideas.
Subjectivity: “Who” often emphasizes the individual or human aspect, making it more personal. “Which” is more neutral, suitable for describing things without personal connotations.
Restrictive vs. Non-Restrictive Clauses: Both “who” and “which” can introduce restrictive (defining) or non-restrictive (additional, non-essential) clauses. However, in non-restrictive clauses, “which” is more commonly used in American English, often set off by commas, while “who” is reserved for persons.

Real-World Examples and Usage Contexts

To understand how “who” and “which” function in actual sentences, consider these examples:

Using “Who”:

The artist who painted this portrait is renowned worldwide.
Students who study regularly tend to perform better in exams.
The woman who called earlier left a message.

Using “Which”:

The car which I bought last year has had no issues.

The book which is on the table belongs to Sarah.
The idea which he proposed was innovative.

Note how “who” is used when referring to people, and “which” when referring to objects or animals. Additionally, in non-restrictive clauses, a comma often precedes “which”:

The painting, which was created in 1920, is a masterpiece.

Common Questions and Misconceptions

A frequent question is whether “which” can refer to people. While in formal English, “which” can sometimes refer to animals or objects, it is generally incorrect to use “which” for humans in restrictive clauses. Instead, “who” should be used. For example:

Incorrect: The boy which won the race is my brother.
Correct: The boy who won the race is my brother.

Some might wonder if “who” can be used for objects or things. The answer is no; “who” is reserved for people. Using it for objects can sound awkward or incorrect.

Another misconception is the interchangeable use of “that” and “which.” In restrictive clauses, both can sometimes be used, but style guides often prefer “that” for essential information and “which” for non-essential, especially in American English. For example:

The book that has a red cover is mine. (restrictive)
The book, which has a red cover, is mine. (non-restrictive)

Practical Takeaway for Choosing Between “Who” and “Which”

To decide whether to use “who” or “which,” follow these simple steps:

Identify whether the noun you are describing is a person or an entity regarded as a person. If yes, use “who”.
If the noun is an animal (considered as a sentient being), object, or abstract concept, use “which”.
For non-essential information in non-restrictive clauses, remember that in American English, “which” is often set off by commas, while “who” is used for people.

Be mindful of style guides and regional preferences—British English sometimes uses “which” more flexibly.

Applying these guidelines ensures clarity and grammatical correctness, making your writing more professional and easier to understand.

Who vs Which: What’s the Difference?