Every week I will demonstrate an example of poor English where a different word is used from the one intended. Sometimes this creates a grammatically incorrect sentence. Unfortunately, the mistake is usually so pervasive that we all do it and such errors are usually made by those who should know better – journalists working for national or global media outlets such as newspapers and television
That / Which
This is one that stumps me from time to time and from the number of resources that attempt to explain the difference, it stumps a lot of other people too. The major difference is that one is a restrictive clause and the other is a non-restrictive clause
Restrictive Clause – That
This limits the sentence to the thing that is being described.
“Cars that are white get dirty easily”. This limits the general “cars” which could be any size, any shape and any colour to “white cars”.
Non-restrictive Clause – Which
“I have a white car and it gets dirty easily, which means I have to wash it more often” which is usually used as a follow on or to clarify something.
I found a great example on Quick and Dirty Tips
Leaves, which are green… suggests that all leaves are green when they are not
Leaves that are green… limits or restricts the point being made in the sentence specifically to green leaves