RedPen Editing
That versus which

‘That’ and ‘which’ are examples of relative pronouns. How these two relative pronouns are used, that is, the role that they play within a sentence, determines which of them is the correct choice.

‘That’ is used (restrictively) to narrow a category or identify a particular instance.

• Any house that is near a bus stop will suit us.

‘Which’ is used (non-restrictively) to add information about something that has already been identified.

• The Grange, which is situated on a bus route, is an ideal home for us.

Notice that the ‘which’ clause is preceded by a comma – and that whole clause could be removed, without losing the grammatical sense of the sentence.

• The Grange, which is situated on a bus route, is an ideal home for us.
• The Grange is an ideal home for us. STILL TRUE

If the ‘that’ clause of the first example is removed, what’s left is no longer true.

• Any house that is near a bus stop will suit us.
• Any house will suit us? NOT TRUE

‘Which’ might be used (restrictively) when preceded by a pronoun:

• The house in which I was born has been sold.