I like to read books that you like. I read the books you told me to, which you left on the table.
That [THINK: restrictive; limits meaning; no comma]
Which [THINK: nonrestrictive; supply extra info; comma required]
“In formal American English, that is used in restrictive clauses, and which in used in nonrestrictive clauses.”
“A restrictive clause contains information that limits the meaning of the thing being talked about….Note that in restrictive clauses, sometimes that can be omitted.”
A nonrestrictive clause…is used to supply additional information that is not essential to understanding the main point of the sentence…it adds extra information, almost like an aside. You could delete the details…and the sentence would still make sense.”
[read more about it on blog.dictionary.com]