Ask the wise old owl
What is the difference between “which” and “that”?
Often these words are used interchangeably, but there is a difference.
The part of the sentence with “which” is usually surrounded by commas and the sentence would make sense without it. This part of the sentence just gives additional information.
Look at these two sentences:
1. The expensive ornament, which was in the lounge, was broken.
2. The expensive ornament that was in the lounge was broken.
In sentence one, the “which was in the lounge”, just gives us additional information about the expensive ornament.
Sentence two suggests that there are a number of expensive ornaments, but we are referring specifically to the one in the lounge. If the “that was in the lounge” were taken away, the sentence would not be complete because we don’t know which expensive ornament was damaged.