That vs. Which: what's the difference?
Thanks for asking.
Technically, you use the word that before a restrictive clause: anything you can't do without. If taking the clause out of the sentence would completely alter the meaning, then the clause is restrictive.
You use the word which before any other type of clause. If you can take it out of the sentence without altering the meaning a lot, then which is your best bet.
NB: You need a comma before which (because anything restrictive needs commas) and not before that.
"A fresh bouquet of roses that smelled wonderful was sitting on the kitchen table."
"A fresh bouquet of roses, which smelled wonderful, was sitting on the kitchen table."
The second sentence is correct because you could remove the clause which smelled wonderful and not affect the meaning of the sentence.
"That orchid was the one that smelled like chocolate."
"That orchid was the one which smelled like chocolate."
Take out the clause "which smelled like chocolate," and you're left with… not a whole lot. That means it's a restrictive clause, and you need to use that. Also, talk about a great housewarming gift.