You made a good attempt at explaining the difference between the relative pronouns "that" and "which," but there are a few areas that could be clarified and refined for precision. Here’s a corrected version of your explanation:
The relative pronoun "that" is used with essential clauses (also known as restrictive clauses), which provide crucial information about the noun they modify. These clauses are necessary for the meaning of the sentence; without them, the sentence may be unclear or lose its intended meaning.
On the other hand, the relative pronoun "which" is used with nonessential clauses (also known as non-restrictive clauses), which provide additional, non-crucial information about the noun they modify. These clauses can be omitted without altering the fundamental meaning of the sentence.
In summary, "that" introduces essential clauses that are critical to the meaning of the sentence, while "which" introduces nonessential clauses that offer extra information.
This version clarifies some terms and provides a clearer distinction between essential and nonessential clauses. It also corrects the phrasing regarding the information provided by "that" and "which."