don_rajesh200 said:
what is the difference between that&which
If you are asking about that versus which as relative pronouns, there is some difference bewteen American English and British English.
In AE, we tend to use "that" in restrictive/defining relative clauses -- those that are necessary for the sentence's meaning. We use "which" for non-defining/non-restrictive relative clauses -- those that simply add additional information. Non-defining/non-restrictive clauses are set off from the rest of the sentence with commas.
In BE, they use either "that" or "which" for restrictive clauses and only "which" for non-restrictive clauses.
AE: New York is the US city that hosts the United Nations.
BE: New York is the US city that/which hosts the United Nations.
Both: New York City, which has 8 million residents, hosts the United Nations.